feat(app): add crash visibility, memory relief, and clipboard reply work

Squashes the working tree that had accumulated on cloud-agent. Two
strands of work, kept in one commit at the maintainer's request.

Crash and stability (this session):

- Subscribe to MetricKit so crash, hang, CPU, and disk-write diagnostics
  are recorded on device. Keyboard-extension memory kills are the most
  likely way a user loses the keyboard mid-sentence and iOS does not
  classify them as crashes, so they never reach App Store Connect.
- Upload those reports to POST /v1/analytics/diagnostics from internal
  builds only (local Debug and TestFlight), reusing the analytics
  installation identifier and skipping entirely when analytics are off.
  App Store builds keep everything on device.
- Shed the Chinese engine, English lexicon, and in-flight pipeline work
  at the 40 MiB and 48 MiB budget thresholds instead of waiting for a
  system memory warning that jetsam often preempts.
- Install audio taps with the input node's live format through one
  shared adaptive resampler, so an audio-route change mid-recording no
  longer raises an uncatchable format-mismatch exception. Covers the
  dictation preview and the Mac recorder, which still used the pattern
  the Flow capture path had already moved away from.
- Harden the librime bridge: never pass a nil string across a nonnull
  boundary when a user dictionary holds malformed UTF-8, null-check the
  engine API vector, and distrust a candidate count without its array.
- Guard the expanded candidate grid against a list that shrinks while
  the collection view is still laying out against the previous count.
- Resolve localized text without the App Group so the screen shown when
  that container is missing renders its message instead of crashing on
  launch, which is the one situation it exists to handle.
- Gate CI on the App Group and Keychain wiring that the keyboard
  extension hard-depends on, with a self-test proving the check fails.

Clipboard, reply, and semantics (pre-existing working tree):

- Unify the reply center, refresh keyboard AI features, and add native
  event and reminder exporters.
- Expand clipboard semantic routing with authored corpora and a
  product-blind holdout, plus the scripts that build and validate them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

OSGKeyboardTests/AppL10nFallbackTests.swift

@@ -0,0 +1,65 @@
+// AppL10nFallbackTests.swift
+// OSGKeyboard · Tests
+//
+// `AppGroupErrorView` is the screen the app shows when the App Group container
+// is missing — its whole job is to turn a provisioning mistake into a readable
+// message instead of a crash loop. It is built entirely from localized strings,
+// so the moment `AppL10n` started resolving the UI language through
+// `ProviderConfig` (which itself requires the App Group and traps without one)
+// that screen crashed on launch, every launch, for exactly the users it exists
+// to help.
+//
+// These tests run in an unsigned host where `AppGroup.isAvailable` is false, so
+// they exercise the real failure path rather than a simulation of it.
+
+@testable import OSGKeyboard
+@testable import OSGKeyboardShared
+import XCTest
+
+final class AppL10nFallbackTests: XCTestCase {
+    func testLocalizationResolvesWithoutAnAppGroup() throws {
+        try XCTSkipIf(
+            AppGroup.isAvailable,
+            "Needs an unsigned host without an App Group container — the case the fallback exists for."
+        )
+
+        // Trapping here is the regression: this must return text, not crash.
+        let title = AppL10n.string("appGroup.error.title")
+
+        XCTAssertFalse(title.isEmpty)
+        XCTAssertNotEqual(
+            title,
+            "appGroup.error.title",
+            "the key came back unresolved, so the error screen would show a raw key"
+        )
+    }
+
+    func testEveryStringOnTheAppGroupErrorScreenResolves() throws {
+        try XCTSkipIf(AppGroup.isAvailable, "Needs an unsigned host without an App Group container.")
+
+        for key in [
+            "appGroup.error.title",
+            "appGroup.error.body",
+            "appGroup.error.step1",
+            "appGroup.error.step2",
+            "appGroup.error.step3"
+        ] {
+            let value = AppL10n.string(key)
+            XCTAssertFalse(value.isEmpty, "\(key) resolved to an empty string")
+            XCTAssertNotEqual(value, key, "\(key) is missing from Localizable.strings")
+        }
+    }
+
+    func testExplicitLanguageStillWinsWithoutAnAppGroup() throws {
+        try XCTSkipIf(AppGroup.isAvailable, "Needs an unsigned host without an App Group container.")
+
+        // The fallback must only supply a *default*; a caller that knows the
+        // language must still be honoured.
+        let english = AppL10n.string("appGroup.error.title", language: .english)
+        let chinese = AppL10n.string("appGroup.error.title", language: .chinese)
+
+        XCTAssertFalse(english.isEmpty)
+        XCTAssertFalse(chinese.isEmpty)
+        XCTAssertNotEqual(english, chinese)
+    }
+}