feat: local HTTP control API for external recording start/stop

[ryanhugh]

What

Adds a localhost-only HTTP control API (127.0.0.1:5172) inside the Tauri app so other local processes (scripts, Raycast, window managers, automations) can control recordings:

Endpoint	Description
GET /status	{"recording": bool}
POST /start	Body {"title"?: string, "metadata"?: string} — starts a recording. Optional custom meeting title; optional free-form metadata block that is saved as the first transcript segment (top of the meeting, included in summarization). Returns 200 once recording actually starts, 409 if already recording, 504 if the frontend refuses (e.g. no transcription model).
POST /stop	Stops the recording and runs the normal save flow (transcription flush → SQLite save → navigation). 409 if not recording.

Example:

curl -X POST http://127.0.0.1:5172/start \
  -H 'content-type: application/json' \
  -d '{"title": "Standup", "metadata": "Attendees: Ryan, Alice\nTicket: ENG-123"}'

curl -X POST http://127.0.0.1:5172/stop

How

The API deliberately reuses the existing tray mechanisms rather than inventing a new path:

• Start stages parameters in sessionStorage and triggers the same auto-start flow the tray uses (useRecordingStart), so model checks, device selection, meeting state, and save flow behave exactly like a button click.
• Stop uses a new shared recording_commands::stop_recording_and_notify() helper — both tray handlers were duplicating ~30 lines of this logic and now call the same helper.
• Metadata is injected as a synthetic transcript segment (sequence_id: -1, sorts before all real segments) both live and at save time, so it survives mid-recording page reloads and state resyncs.
• Server is axum on the existing tokio runtime, bound to 127.0.0.1 only (same trust level as the tray). Bind failure logs and degrades gracefully.

Pre-existing bugs fixed along the way

1. Selected devices and meeting name were silently dropped on every recording start: recordingService.startRecordingWithDevices passed snake_case arg keys (mic_device_name, meeting_name) to a Tauri v2 command expecting camelCase, so Rust always received None (log: Mic: None, System: None, Meeting: None) and every meeting got the default Meeting YYYY-MM-DD… title regardless of the UI-generated one.
2. Clean builds of main fail with the committed Cargo.lock (tauri 2.11.2): generate_handler! requires the generated __tauri_command_name_* macros, but summary/mod.rs and summary_engine/mod.rs re-exported only the old __cmd__* ones → 15 × E0433. Added the missing re-exports.

Testing

Verified end-to-end on macOS (Apple Silicon, dev build):

• GET /status → {"recording":false} / {"recording":true} ✅
• POST /start with title + metadata → app navigates home, recording starts, 200 {"status":"recording","title":"API Test Round 2"}; Rust log confirms Meeting: Some("API Test Round 2") ✅
• POST /start while recording → 409 ✅ ; POST /stop while idle → 409 ✅
• Spoke during recording, then POST /stop → normal save flow; SQLite shows the meeting titled API Test Round 2 with the metadata block as the first segment (audio_start_time = 0) followed by the real transcribed speech ✅
• cargo check and tsc --noEmit clean ✅

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