feat: Meeting Assistant MVP - Complete implementation

Enterprise Meeting Knowledge Management System with:

Backend (FastAPI):
- Authentication proxy with JWT (pj-auth-api integration)
- MySQL database with 4 tables (users, meetings, conclusions, actions)
- Meeting CRUD with system code generation (C-YYYYMMDD-XX, A-YYYYMMDD-XX)
- Dify LLM integration for AI summarization
- Excel export with openpyxl
- 20 unit tests (all passing)

Client (Electron):
- Login page with company auth
- Meeting list with create/delete
- Meeting detail with real-time transcription
- Editable transcript textarea (single block, easy editing)
- AI summarization with conclusions/action items
- 5-second segment recording (efficient for long meetings)

Sidecar (Python):
- faster-whisper medium model with int8 quantization
- ONNX Runtime VAD (lightweight, ~20MB vs PyTorch ~2GB)
- Chinese punctuation processing
- OpenCC for Traditional Chinese conversion
- Anti-hallucination parameters
- Auto-cleanup of temp audio files

OpenSpec:
- add-meeting-assistant-mvp (47 tasks, archived)
- add-realtime-transcription (29 tasks, archived)

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

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

openspec/changes/archive/2025-12-10-add-realtime-transcription/proposal.md

@@ -0,0 +1,24 @@
+# Change: Add Real-time Streaming Transcription
+
+## Why
+Current transcription workflow requires users to stop recording before seeing results. Users cannot edit transcription errors, and output lacks punctuation. For meeting scenarios, real-time feedback with editable text is essential for immediate correction and context awareness.
+
+## What Changes
+- **Sidecar**: Implement streaming VAD-based transcription with sentence segmentation
+- **IPC**: Add continuous audio streaming from renderer to main process to sidecar
+- **Frontend**: Make transcript editable with real-time segment updates
+- **Punctuation**: Enable Whisper's word timestamps and add sentence boundary detection
+
+## Impact
+- Affected specs: `transcription` (new), `frontend-transcript` (new)
+- Affected code:
+  - `sidecar/transcriber.py` - Add streaming mode with VAD
+  - `client/src/main.js` - Add audio streaming IPC handlers
+  - `client/src/preload.js` - Expose streaming APIs
+  - `client/src/pages/meeting-detail.html` - Editable transcript component
+
+## Success Criteria
+1. User sees text appearing within 2-3 seconds of speaking
+2. Each segment is individually editable
+3. Output includes punctuation (。，？！)
+4. Recording can continue while user edits previous segments