feat: comprehensive rewrite — push-to-talk pipeline, Typeless UI, Chinese

This is a major rewrite of OpenLessKeyboard, renamed to OSGKeyboard
and rebuilt end-to-end. 59 files changed (+3205/-1550).

Architecture
------------
- Rename project, targets, directories from OpenLess* to OSGKeyboard*
  (OpenLess / OpenLessKeyboard / OpenLessShared / OpenLessTests).
- AudioCaptureService rewritten as @unchecked Sendable class with
  OSAllocatedUnfairLock instead of an actor, so it survives Swift 6
  strict-concurrency checks while still serialising engine + converter
  state correctly.
- Single design system (Palette / Spacing / Radius / TypeStyle /
  Motion) lifted into OSGKeyboardShared so the host app and the
  keyboard extension stay in lock-step.

Push-to-talk — first-principles fix
-----------------------------------
- App Group + audio-input entitlements were stripped by Xcode's
  Automatic Signing. They are now declared in project.yml so
  'xcodegen generate' re-emits them every time. iOS Developer
  Account is untouched; only the App Group capability was added.
- State machine uses a real stored `phase` (was a derived shim
  that locked out every press after the first because
  recordStream was never nilled after the pipeline finished).
- Microphone permission is requested inside pressBegan (async
  Task) so the press flow optimistically enters .recording;
  permission denial surfaces a short error and returns to idle.
- Replaced LongPressGesture(0.15s) with a DragGesture +
  TapGesture pair separated by pressArmed, so a single tap no
  longer fires both onPressBegan and onTap simultaneously.
- Real RMS / peak level meter from the AVAudioEngine tap (was a
  pseudo-random walk); the visible waveform is now driven by
  actual audio.
- SFSpeechRecognizer(locale:) with selectable ASR locales
  (auto / zh-Hans / zh-Hant / en-US / ja-JP / ko-KR) for
  first-class Chinese / English / Japanese / Korean dictation,
  with on-device recognition when supported.
- AVAudioSession now deactivates on stop so other apps' audio
  routing is restored.

Keyboard UI — Typeless-inspired layout
---------------------------------------
- Hero area is 280 pt with a 96 pt record disc, breathing outer
  ring, and a 12-bar waveform driven by the real RMS.
- inputView.allowsSelfSizing + a heightAnchor constraint so iOS
  no longer crops the keyboard under the Spotlight bar / home
  indicator.
- Top bar: mode chip (Off / 转写 / 润色) + locale chip
  (Auto / 简体 / 繁體 / EN / 日 / 한) + status badge + ⚙.
- Bottom bar: globe / delete / 空格 / return — all 40 pt and
  balanced.
- RecordButton onPressEnded is now safe to fire from a quick
  press; pressArmed prevents double-firing.

LLM / Polishing
---------------
- LLMClient: stopped leaking the server response body in errors
  (server body is now logged at debug, never surfaced to UI);
  added a dedicated .rateLimited case for 429.
- PolishingService timeout 8s → 12s to accommodate slower
  domestic LLM providers.
- AppGroupStore.defaultSystemPrompt is now provider-aware
  (Chinese for zhipu/moonshot/qwen/deepseek, English otherwise).

Onboarding & Settings
---------------------
- Re-themed OnboardingView / HomeView / SettingsView on the
  new design system.
- ProviderPickerSection now shows 6 providers (OpenAI, DeepSeek,
  Qwen DashScope, 智谱 GLM, 月之暗面 Moonshot, Custom) with
  blurb + selected accent.
- PickerRow for Mode and ASR locale; System Prompt editor with
  reset-to-default.
- API settings page "Get an API key" used SwiftUI Link, which
  has a hit-test bug on iOS 18 that ate gestures from adjacent
  TextFields (manifested as "typing jumps to a website"). It is
  now an explicit Button + contentShape + .submitLabel(.done) on
  the fields.

Polish & tests
--------------
- LLMClientTests: 4 unit tests passing (ProviderConfig
  persistence + OpenAI request/response + HTTP error + missing
  key); test App Group renamed to the correct identifier.
- ProviderConfig.apply now captures the previous provider id
  *before* mutating, so switching providers actually resets the
  system prompt to the new default.

Build
-----
- Swift 6 strict concurrency, iOS 18.0 deployment target.
- Tested on Xcode 26 + iPhone 17 Pro simulator. A real device on
  iOS 27 beta aborts with __abort_with_payload (dispatch
  library ABI mismatch); use an iOS 18 real device or the
  iOS 26 simulator for now.

🤖 Generated with Claude Code

OSGKeyboardShared/Services/LLMClient.swift

@@ -0,0 +1,125 @@
+// LLMClient.swift
+// OSGKeyboard · Shared
+//
+// Protocol-based LLM client. Default implementation is the OpenAI-compatible
+// chat completion client. Add other impls (Anthropic, Gemini) as needed.
+
+import Foundation
+
+public enum LLMError: Error, LocalizedError, Sendable {
+    case invalidURL
+    case noAPIKey
+    case http(status: Int)
+    case decoding(String)
+    case transport(String)
+    case cancelled
+    case rateLimited
+
+    public var errorDescription: String? {
+        switch self {
+        case .invalidURL:    return "API 地址无效。请在设置中检查 Base URL。"
+        case .noAPIKey:      return "未填写 API Key。"
+        case .http(let s):   return "API 返回 HTTP \(s)。请稍后重试或联系服务方。"
+        case .decoding:      return "解析 API 响应失败。"
+        case .transport:     return "网络错误,请检查连接后重试。"
+        case .rateLimited:   return "API 调用过于频繁,请稍候再试。"
+        case .cancelled:     return "请求已取消。"
+        }
+    }
+}
+
+public protocol LLMClient: Sendable {
+    func polish(_ text: String, systemPrompt: String) async throws -> String
+}
+
+// MARK: - OpenAI-compatible implementation
+
+public struct OpenAICompatibleClient: LLMClient {
+    public let baseURL: String
+    public let apiKey: String
+    public let model: String
+    public let session: URLSession
+
+    public init(
+        baseURL: String,
+        apiKey: String,
+        model: String,
+        session: URLSession = .shared
+    ) {
+        self.baseURL = baseURL
+        self.apiKey = apiKey
+        self.model = model
+        self.session = session
+    }
+
+    public func polish(_ text: String, systemPrompt: String) async throws -> String {
+        guard !apiKey.isEmpty else { throw LLMError.noAPIKey }
+
+        let urlString = baseURL.hasSuffix("/")
+            ? "\(baseURL)chat/completions"
+            : "\(baseURL)/chat/completions"
+        guard let url = URL(string: urlString) else { throw LLMError.invalidURL }
+
+        let request = LLMRequest(
+            model: model,
+            messages: [
+                .system(systemPrompt),
+                .user(text)
+            ],
+            temperature: 0.3,
+            maxTokens: nil
+        )
+
+        var req = URLRequest(url: url)
+        req.httpMethod = "POST"
+        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        req.setValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
+        req.timeoutInterval = 15
+
+        let encoder = JSONEncoder()
+        req.httpBody = try encoder.encode(request)
+
+        do {
+            let (data, response) = try await session.data(for: req)
+            guard let http = response as? HTTPURLResponse else {
+                throw LLMError.transport("non-HTTP response")
+            }
+            if !(200..<300).contains(http.statusCode) {
+                #if DEBUG
+                // Log full body for debugging — never expose to UI.
+                let body = String(data: data, encoding: .utf8) ?? ""
+                print("⚠️ LLM HTTP \(http.statusCode): \(body.prefix(500))")
+                #endif
+                if http.statusCode == 429 { throw LLMError.rateLimited }
+                throw LLMError.http(status: http.statusCode)
+            }
+            do {
+                let decoded = try JSONDecoder().decode(LLMResponse.self, from: data)
+                return decoded.content.trimmingCharacters(in: .whitespacesAndNewlines)
+            } catch {
+                throw LLMError.decoding(String(describing: error))
+            }
+        } catch let err as LLMError {
+            throw err
+        } catch is CancellationError {
+            throw LLMError.cancelled
+        } catch let urlError as URLError where urlError.code == .cancelled {
+            throw LLMError.cancelled
+        } catch {
+            throw LLMError.transport(String(describing: error))
+        }
+    }
+}
+
+// MARK: - Factory
+
+public enum LLMClientFactory {
+    /// Build a client from the current `ProviderConfig`.
+    public static func make(from config: ProviderConfig) -> LLMClient {
+        OpenAICompatibleClient(
+            baseURL: config.baseURL,
+            apiKey: config.apiKey,
+            model: config.model
+        )
+    }
+}