Add voice notes: on-device transcription, multi-language, watch capture

- Schema v2: Note.AudioInfo, .m4a sidecar next to the note JSON in iCloud
- AudioRecorderService (iOS/macOS) + SpeechAnalyzer transcription pipeline
  with enabled-language set and confidence-based auto-pick, re-transcribe menu
- Settings > Transcription > Languages with asset download/reserve handling
- watchOS app + accessory complication: one-button recorder, WCSession
  transferFile to phone, WatchInbox staging, direct-upsert ingestion
- Player UI, transcription status chips, quick-capture mic in notes list
- Version 0.2, changelog + README updated

Notes/Services/InstallIdentity.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+/// Stable per-install identifier — a UUID minted once on first access and kept
+/// in UserDefaults for the life of the install. Distinct from the iCloud
+/// account: two devices signed into the same account get different install IDs.
+///
+/// It answers "which device owns a pending transcription?" A voice note stamps
+/// the recording device's `installID` into `AudioInfo.transcriberDeviceID`; only
+/// the device whose `installID` matches transcribes it, while the others render
+/// status only. Re-transcribing on any device reassigns the id to itself, which
+/// is also the recovery path when the original recording device is gone.
+enum InstallIdentity {
+    private static let key = "Notes.installID"
+
+    /// The per-install UUID, created lazily on first read and reused forever.
+    static var installID: String {
+        if let existing = UserDefaults.standard.string(forKey: key) {
+            return existing
+        }
+        let fresh = UUID().uuidString
+        UserDefaults.standard.set(fresh, forKey: key)
+        return fresh
+    }
+}