feat: iCloud settings sync and cold-start return redesign

- Add iCloud key-value settings sync (engine/language/polish/Flow prefs);
  API keys stay on-device. New "Sync settings via iCloud" toggle.
- Redesign cold-start handoff: bottom-bar left-to-right swipe guidance,
  auto-dismiss on app switch, tap-anywhere to close, retained return link.
- Harden keyboard->app handoff with host-disconnected hint.
- Include prior Unreleased ASR fixes (route-change crash, fallback warning,
  multi-utterance recognition, local ASR diagnostics).

Release 0.5.0 (build 18).

OSGKeyboardTests/PersonalDictionaryCloudSyncTests.swift

@@ -8,23 +8,7 @@ import XCTest
 
 // MARK: - Fake KVS
 
-private final class FakeUbiquitousKeyValueStore: UbiquitousKeyValueStoreing, @unchecked Sendable {
-    private var storage: [String: Data] = [:]
-
-    func data(forKey key: String) -> Data? {
-        storage[key]
-    }
-
-    func set(_ value: Data?, forKey key: String) {
-        if let value {
-            storage[key] = value
-        } else {
-            storage.removeValue(forKey: key)
-        }
-    }
-
-    func synchronize() -> Bool { true }
-}
+// See FakeUbiquitousKeyValueStore.swift
 
 // MARK: - Tests
 
@@ -170,6 +154,7 @@ final class PersonalDictionaryCloudSyncTests: XCTestCase {
         try await sync.enableSync()
 
         XCTAssertTrue(store.personalDictionaryICloudSyncEnabled)
+        XCTAssertEqual(kvs.object(forKey: ICloudSyncPreferences.dictionaryEnabledKey) as? Bool, true)
         XCTAssertEqual(Set(store.personalDictionary.entries.map(\.term)), Set(["LocalTerm", "RemoteTerm"]))
         XCTAssertNotNil(sync.loadRemote())
     }