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>

OSGKeyboardShared/Services/FlowSessionBridge/FlowSessionBridge+Lifecycle.swift

@@ -87,6 +87,27 @@ extension FlowSessionBridge {
         FlowSessionBridgeStorage.flush(store)
     }
 
+    /// Re-assert the App Group session flag for a host that is provably alive
+    /// (PiP up, fresh heartbeat) but whose flag was cleared out from under it.
+    ///
+    /// A host suspended after a PiP drop keeps `isActive` in memory but stops
+    /// writing heartbeats; the keyboard's `clearIfHostStale()` then reads that
+    /// frozen heartbeat as a dead host and clears `flowSessionActive`. When the
+    /// same process resumes it still owns the session, so it must republish the
+    /// flag — otherwise `isHostReachable()` (and thus `isHostReady()`) can never
+    /// go green again and every `startflow` is rejected. Unlike
+    /// `markSessionActivePersistent`, this preserves any pending command/result/
+    /// ack payloads so a resume mid-delivery is not wiped.
+    public static func reassertSessionActive(defaults: UserDefaults? = nil) {
+        let store = FlowSessionBridgeStorage.resolvedDefaults(defaults)
+        let now = Date().timeIntervalSince1970
+        store.set(true, forKey: FlowSessionKeys.flowSessionActive)
+        store.removeObject(forKey: FlowSessionKeys.flowSessionExpires)
+        store.set(now, forKey: FlowSessionKeys.lastActivityAt)
+        writeHeartbeat(defaults: store)
+        FlowSessionBridgeStorage.flush(store)
+    }
+
     public static func markSessionInactive(defaults: UserDefaults? = nil) {
         let store = FlowSessionBridgeStorage.resolvedDefaults(defaults)
         store.set(false, forKey: FlowSessionKeys.flowSessionActive)
@@ -322,6 +343,31 @@ extension FlowSessionBridge {
         return store.bool(forKey: FlowSessionKeys.flowHostReady)
     }
 
+    /// The host published a *fresh* start-in-progress snapshot for the current
+    /// generation — proof it received the `startflow` request and is alive and
+    /// warming, even though it is not ready yet. A cold-launching host does not
+    /// refresh the heartbeat (see `writeReadySnapshot`), so this reads the
+    /// snapshot's own `heartbeatAt` rather than `isHostReachable()`. Returns the
+    /// starting reason so the caller can distinguish "warming in foreground"
+    /// from "parked waiting for the user to bring the app forward".
+    public static func hostStartInProgress(defaults: UserDefaults? = nil) -> FlowReadySnapshot.Reason? {
+        let store = FlowSessionBridgeStorage.resolvedDefaults(defaults)
+        guard let snapshot = readySnapshot(defaults: store), !snapshot.ready else { return nil }
+        if let snapshotGeneration = snapshot.hostGeneration,
+           let currentGeneration = store.string(forKey: FlowSessionKeys.hostGeneration),
+           snapshotGeneration != currentGeneration {
+            return nil
+        }
+        let age = Date().timeIntervalSince1970 - snapshot.heartbeatAt
+        guard age >= 0, age <= FlowSessionKeys.hostStartAckFreshInterval else { return nil }
+        switch snapshot.reason {
+        case .starting, .waitingForForeground, .waitingForAudioProof:
+            return snapshot.reason
+        default:
+            return nil
+        }
+    }
+
     private static func clearHostReady(defaults: UserDefaults, notify: Bool) {
         defaults.removeObject(forKey: FlowSessionKeys.flowHostReady)
         defaults.removeObject(forKey: FlowSessionKeys.flowHostReadyAt)