chore: Archive all pending OpenSpec proposals

Force archive the following proposals:
- add-audio-device-selector (complete)
- add-embedded-backend-packaging (19/26 tasks)
- add-flexible-deployment-options (20/21 tasks)

New specs created:
- audio-device-management (7 requirements)
- embedded-backend (8 requirements)

Updated specs:
- transcription (+2 requirements for model download progress)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

openspec/specs/transcription/spec.md

@@ -175,3 +175,42 @@ The system SHALL support both real-time local transcription and file-based cloud
 - **WHEN** transcription completes from either source
 - **THEN** result SHALL be displayed in the same transcript area in meeting detail page
 
+### Requirement: Model Download Progress Display
+The sidecar SHALL report Whisper model download progress to enable UI feedback.
+
+#### Scenario: Emit download start
+- **WHEN** Whisper model download begins
+- **THEN** sidecar SHALL emit JSON to stdout: `{"status": "downloading_model", "model": "<size>", "progress": 0, "total_mb": <size>}`
+
+#### Scenario: Emit download progress
+- **WHEN** download progress updates
+- **THEN** sidecar SHALL emit JSON: `{"status": "downloading_model", "progress": <percent>, "downloaded_mb": <current>, "total_mb": <total>}`
+- **AND** progress updates SHALL occur at least every 5% or every 5 seconds
+
+#### Scenario: Emit download complete
+- **WHEN** model download completes
+- **THEN** sidecar SHALL emit JSON: `{"status": "model_downloaded", "model": "<size>"}`
+- **AND** proceed to model loading
+
+#### Scenario: Skip download for cached model
+- **WHEN** model already exists in huggingface cache
+- **THEN** sidecar SHALL NOT emit download progress messages
+- **AND** proceed directly to loading
+
+### Requirement: Frontend Model Download Progress Display
+The Electron frontend SHALL display model download progress to users.
+
+#### Scenario: Show download progress in transcript panel
+- **WHEN** sidecar emits download progress
+- **THEN** whisper status element SHALL display download percentage and size
+- **AND** format: "Downloading: XX% (YYY MB / ZZZ MB)"
+
+#### Scenario: Show download complete
+- **WHEN** sidecar emits model_downloaded status
+- **THEN** whisper status element SHALL briefly show "Model downloaded"
+- **AND** transition to loading state
+
+#### Scenario: Forward progress events via IPC
+- **WHEN** main process receives download progress from sidecar
+- **THEN** it SHALL forward to renderer via `model-download-progress` IPC channel
+