Decouple transcripts from note text; end-to-end watch transfer acks

Schema v3: transcription attempts accumulate on AudioInfo (text, locale,
confidence, forced flag) — latest attempt is displayed, payload.text is
purely user writing, v2 notes migrate at read time. Editor shows the
transcript in its own live-updating section with insert-into-note; search
matches transcripts weighted by confidence. Watch recordings are now
deleted only on the phone's durable-ingest ack (transferUserInfo), closing
every phone-side loss window; failed sidecar writes unstage instead of
orphaning, and unreadable inbox recordings are surfaced in logs.

Claude-Session: https://claude.ai/code/session_014esDWi42URLEC6Cj17hGQ3

NotesTests/NoteDocumentTests.swift

@@ -77,13 +77,13 @@ struct NoteDocumentTests {
     /// A file stamped with a newer schema (and carrying a field this build
     /// doesn't model) must be quarantined by the gate — Codable silently drops
     /// the unknown key, so partial-decoding then rewriting would downgrade it.
-    @Test func forwardGateQuarantinesV3Fixture() throws {
+    @Test func forwardGateQuarantinesNewerFixture() throws {
         let id = ULID(millisecondsSinceEpoch: 1_700_000_000_000, randomHi: 3, randomLo: 4)
         let json = """
         {
           "meta": {
             "id": "\(id.stringValue)",
-            "schemaVersion": 3,
+            "schemaVersion": \(Note.currentSchemaVersion + 1),
             "createdAt": "2023-11-14T22:13:20Z",
             "modifiedAt": "2023-11-14T22:13:20Z"
           },
@@ -98,7 +98,7 @@ struct NoteDocumentTests {
         }
         """
         let note = try DocumentCoder.decode(Note.self, from: Data(json.utf8))
-        #expect(note.meta.schemaVersion == 3)
+        #expect(note.meta.schemaVersion == Note.currentSchemaVersion + 1)
         #expect(!note.isReadable)
     }