feat: harden Flow cold-start/force-quit and polish macOS dictation UX

Fix cold-start overlay recursion that overflowed the main-thread stack when
recording began while the ready overlay was still up; also remove temporary
on-screen Flow DEBUG panels after the orange-mic investigation, and land the
macOS overlay/catalog/layout polish plus related Flow recovery hardening.

OSGKeyboardShared/Services/ICloudSync/AppCloudSync.swift

@@ -39,20 +39,48 @@ public final class AppCloudSync {
             ?? SpeechHistoryCloudSync(kvs: kvs, makeStore: makeStore, historyDefaults: historyDefaults)
     }
 
+    /// Serializes external-change pulls: KVS posts change notifications in
+    /// bursts (one per key at times), and overlapping pull-merge-apply runs
+    /// can interleave their read/write phases. `wantsAnotherPull` coalesces
+    /// every burst into at most one trailing re-pull.
+    private var isPulling = false
+    private var wantsAnotherPull = false
+
     public func startObservingExternalChanges() {
         guard externalChangeObserver == nil else { return }
         externalChangeObserver = NotificationCenter.default.addObserver(
             forName: NSUbiquitousKeyValueStore.didChangeExternallyNotification,
             object: nil,
             queue: .main
-        ) { [weak self] _ in
+        ) { [weak self] note in
             guard let self else { return }
+            // Distinguish WHY the store changed. `.accountChange` means the
+            // user switched iCloud accounts — the incoming values belong to a
+            // DIFFERENT account and must not be merged into this one's data
+            // (deleted-entry resurrection, foreign history, wrong settings).
+            let reason = note.userInfo?[NSUbiquitousKeyValueStoreChangeReasonKey] as? Int
+            if reason == NSUbiquitousKeyValueStoreAccountChange {
+                return
+            }
             Task { @MainActor in
-                await self.pullAllIfEnabled()
+                await self.pullAllCoalesced()
             }
         }
     }
 
+    private func pullAllCoalesced() async {
+        guard !isPulling else {
+            wantsAnotherPull = true
+            return
+        }
+        isPulling = true
+        defer { isPulling = false }
+        repeat {
+            wantsAnotherPull = false
+            await pullAllIfEnabled()
+        } while wantsAnotherPull
+    }
+
     public func stopObservingExternalChanges() {
         if let externalChangeObserver {
             NotificationCenter.default.removeObserver(externalChangeObserver)
@@ -79,18 +107,27 @@ public final class AppCloudSync {
     }
 
     /// Low-risk manual sync: pull remote changes, merge, then push local state.
+    /// Each push runs independently — one payload failing must not abort the
+    /// others (a too-large history would otherwise also kill the dictionary
+    /// push). The first error is rethrown after every push has been tried.
     public func syncNow() async throws {
         let store = makeStore()
         await pullAllIfEnabled()
 
+        var firstError: Error?
+        func attempt(_ body: () async throws -> Void) async {
+            do { try await body() } catch { if firstError == nil { firstError = error } }
+        }
+
         if store.settingsICloudSyncEnabled {
-            try await settingsSync.pushLocalIfEnabled()
-            try await usageStatisticsSync.pushLocalIfEnabled()
-            try await speechHistorySync.pushLocalIfEnabled()
+            await attempt { try await settingsSync.pushLocalIfEnabled() }
+            await attempt { try await usageStatisticsSync.pushLocalIfEnabled() }
+            await attempt { try await speechHistorySync.pushLocalIfEnabled() }
         }
         if store.personalDictionaryICloudSyncEnabled {
-            try await dictionarySync.pushLocalIfEnabled(store.personalDictionary)
+            await attempt { try await dictionarySync.pushLocalIfEnabled(store.personalDictionary) }
         }
+        if let firstError { throw firstError }
     }
 
     public var settingsSyncService: SettingsCloudSync { settingsSync }