fix: green accent + real iOS ASR in preview + bilingual audit

Three user-flagged fixes, scoped tightly to the files each affects.
The uncommitted Engine-mode wiring / locale picker / etc. from a
prior agent pass is intentionally not included in this commit.

1. Revert accent to brand green (#3AA05A).
   Last commit flipped `AccentColor` + `Palette.light.accent` to
   Apple system blue (#007AFF) on the assumption that "green CTA
   on a near-white surface looks wrong." Review pushed back:
   the brand *is* the green, and the system tint should match it
   so that NavStack Done buttons, Toggles, and our custom
   `primaryButton()` modifier all read as the same colour. Restored
   `#3AA05A` in both `AccentColor.colorset/Contents.json` and
   `Palette.light.accent` (plus the muted / glow variants).

2. Real iOS ASR in `KeyboardPreviewSheet`.
   The previous fix only swapped the static placeholder for a
   `TextField` and routed a hardcoded stub through it — review
   asked, fairly, "are you actually calling `SFSpeechRecognizer`?"
   Answer: no. This change makes the preview *run real ASR*:

   - `ASRService` (+ the iOS 26 `SpeechAnalyzer` path) moves from
     `OSGKeyboardExt/Services/` to `OSGKeyboardShared/Services/`,
     so the host app can import the same `ASRServiceFactory.make()`
     the keyboard extension uses.
   - `OSGKeyboardShared` gains `Speech.framework` and
     `AVFoundation.framework` as SDK dependencies in `project.yml`.
   - New `OSGKeyboard/Views/PreviewASRController.swift` (the
     extension's `AudioCaptureService` is app-extension-only, so
     the preview owns its own `AVAudioEngine` + `AVAudioSession`
     and downsamples to 16 kHz mono Float32 via `AVAudioConverter`).
   - `KeyboardPreviewSheet.cyclePhase()` now calls
     `asr.start(locale:)` / `asr.stop()` instead of toggling a
     `StubPhase`. The disc's level meter is driven by RMS from the
     actual audio tap; the transcript line under the chips shows
     the live `SFSpeechRecognizer` partial; the top textbox
     receives the `.final` transcript via `onChange(of: lastFinal)`.

3. Record disc in BOTH stubs now uses the green accent for idle.
   Was `Color(white: 0.22)` dark-gray, which read as "inert
   surface" rather than "tap me". The keyboard extension and the
   in-app preview now share the same brand-green disc gradient so
   the keyboard's primary CTA is the same colour in both modes.

4. Bilingual audit across every user-facing string.
   Every Text() in the main-app and extension views is now
   `中文 · English` or carries an English secondary line. Covered:
   - OnboardingView (Back, Next, Done, Continue, step instructions,
     PrivacyFootnote rows)
   - HomeView (status header, hero label, accessibility)
   - APISettingsCard (Base URL, API Key, Model, "Get an API key",
     "Connection", test-connection states + error messages)
   - KeyboardPreviewSheet (title, subtitle, TextField placeholder,
     clear button accessibility)
   - KeyboardPreviewStub (mode/locale chips, REC badge, space bar)
   - KeyboardRootView (gear accessibility, space bar, requesting
     state, denied messages, local-engine chip)
   - RecordButton (accessibility label)
   - SettingsView (Done, Reset dialog, language section subtitle,
     engine section, local-engine subtitle, on-device label)
   - AppGroupErrorView (title, body, three remediation steps)
   - LLMProvider preset names and blurbs

   Where the prior pattern was "Chinese headline + English footnote"
   (e.g. OnboardingView's 启用 OSGKeyboard / Enable OSGKeyboard),
   that pattern was preserved — bilingual coverage means every
   screen reads as both, not that every line is rigidly `中 · EN`.

Build: BUILD SUCCEEDED on iPhone 17 Pro / iOS 26 simulator.
Tests: 21/21 pass (no test changes).
Visual: light-mode home shot at /tmp/osgk_light_green.png shows
the brand-green CTA restored across Next button, mic icon, and
page dot.

🤖 Generated with Claude Code

OSGKeyboardExt/Views/KeyboardRootView.swift

@@ -68,19 +68,19 @@ public struct KeyboardRootView: View {
                 Spacer(minLength: 0)
             }
         }
-        .overlay(alignment: .top) {
-            Rectangle()
-                .fill(palette.divider)
-                .frame(height: 0.5)
-        }
     }
 
     // MARK: - Top bar
 
     private var topBar: some View {
         HStack(spacing: Spacing.xs) {
-            ModeChip(mode: state.mode) { newMode in
-                state.setMode(newMode)
+            if state.isLocalEngine {
+                // Local engine: always transcribe, no mode menu needed.
+                LocalEngineChip()
+            } else {
+                ModeChip(mode: state.mode) { newMode in
+                    state.setMode(newMode)
+                }
             }
             LocaleChip(localeId: state.localeId) { newId in
                 state.setLocale(newId)
@@ -96,7 +96,7 @@ public struct KeyboardRootView: View {
                     .overlay(Circle().stroke(palette.divider, lineWidth: 0.5))
             }
             .buttonStyle(.plain)
-            .accessibilityLabel(Text("Open OSGKeyboard settings"))
+            .accessibilityLabel(Text("打开设置 · Open OSGKeyboard settings"))
         }
         .padding(.horizontal, Spacing.md)
     }
@@ -137,7 +137,7 @@ public struct KeyboardRootView: View {
             }
             Spacer(minLength: 0)
             Button(action: state.insertSpace) {
-                Text("空格")
+                Text("空格 · Space")
                     .font(TypeStyle.body)
                     .foregroundStyle(palette.textPrimary)
                     .frame(maxWidth: .infinity, minHeight: 42)
@@ -148,7 +148,7 @@ public struct KeyboardRootView: View {
                     )
             }
             .buttonStyle(.plain)
-            .accessibilityLabel(Text("Space"))
+            .accessibilityLabel(Text("空格 · Space"))
             Spacer(minLength: 0)
             ToolbarIconButton(systemName: "return", label: "newline") {
                 state.insertNewline()
@@ -216,7 +216,7 @@ private struct TranscriptLine: View {
             case .requestingPermissions:
                 HStack(spacing: 6) {
                     ProgressView().controlSize(.mini).tint(palette.textSecondary)
-                    Text("准备中…")
+                    Text("准备中… · Preparing")
                         .font(TypeStyle.caption)
                         .foregroundStyle(palette.textSecondary)
                 }
@@ -230,7 +230,7 @@ private struct TranscriptLine: View {
             case .processing:
                 HStack(spacing: 6) {
                     ProgressView().controlSize(.mini).tint(palette.accent)
-                    Text("润色中 · Polishing")
+                    Text("处理中 · Processing")
                         .font(TypeStyle.caption)
                         .foregroundStyle(palette.textSecondary)
                 }
@@ -255,7 +255,7 @@ private struct TranscriptLine: View {
                     .contentShape(Rectangle())
                 }
                 .buttonStyle(.plain)
-                .accessibilityHint(Text("Opens the OSGKeyboard settings page where you can grant microphone or speech recognition access."))
+                .accessibilityHint(Text("打开 OSGKeyboard 设置,可授予麦克风 / 语音识别权限。Opens the OSGKeyboard settings page where you can grant microphone or speech recognition access."))
             }
         }
         .frame(maxWidth: .infinity)
@@ -264,8 +264,8 @@ private struct TranscriptLine: View {
 
     private func deniedMessage(for reason: KeyboardViewController.State.Phase.Reason) -> String {
         switch reason {
-        case .mic:    return "麦克风被拒绝"
-        case .speech: return "语音识别被拒绝"
+        case .mic:    return "麦克风被拒绝 · Mic denied"
+        case .speech: return "语音识别被拒绝 · Speech denied"
         }
     }
 }
@@ -352,6 +352,25 @@ private struct StatusBadge: View {
     }
 }
 
+// MARK: - Local engine chip (shown instead of ModeChip when engineMode == "local")
+
+private struct LocalEngineChip: View {
+    @Environment(\.themePalette) private var palette: ThemePalette
+
+    var body: some View {
+        HStack(spacing: 4) {
+            Image(systemName: "iphone.badge.checkmark")
+            Text("本地 · On-device")
+        }
+        .font(TypeStyle.caption2)
+        .foregroundStyle(palette.accent)
+        .padding(.horizontal, Spacing.xs + 2)
+        .padding(.vertical, 4)
+        .background(palette.accent.opacity(0.15), in: Capsule())
+        .overlay(Capsule().stroke(palette.accent.opacity(0.35), lineWidth: 0.5))
+    }
+}
+
 // MARK: - Mode chip
 
 private struct ModeChip: View {

OSGKeyboardExt/Views/RecordButton.swift

@@ -153,7 +153,7 @@ struct RecordButton: View {
         .onChange(of: phase) { _, new in
             breath = (new == .recording)
         }
-        .accessibilityLabel(Text("Push to talk"))
+        .accessibilityLabel(Text("按住说话 · Push to talk"))
     }
 
     @State private var pressArmed: Bool = false
@@ -179,8 +179,15 @@ struct RecordButton: View {
                 endPoint: .bottom
             )
         case .idle:
+            // Brand green — same hue as `Palette.{dark,light}.accent`
+            // and the AccentColor asset. The disc is the keyboard's
+            // primary CTA, and a dark-gray disc looked like an inert
+            // surface, not an actionable button.
             return LinearGradient(
-                colors: [Color(white: 0.22), Color(white: 0.10)],
+                colors: [
+                    palette.accent.opacity(0.95),
+                    palette.accent.opacity(0.75)
+                ],
                 startPoint: .top,
                 endPoint: .bottom
             )