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>

client/src/preload.js

@@ -0,0 +1,32 @@
+const { contextBridge, ipcRenderer } = require("electron");
+
+contextBridge.exposeInMainWorld("electronAPI", {
+  // Navigation
+  navigate: (page) => ipcRenderer.invoke("navigate", page),
+
+  // Sidecar status
+  getSidecarStatus: () => ipcRenderer.invoke("get-sidecar-status"),
+
+  // === Streaming Mode APIs ===
+  startRecordingStream: () => ipcRenderer.invoke("start-recording-stream"),
+  streamAudioChunk: (base64Audio) => ipcRenderer.invoke("stream-audio-chunk", base64Audio),
+  stopRecordingStream: () => ipcRenderer.invoke("stop-recording-stream"),
+
+  // Streaming events
+  onTranscriptionSegment: (callback) => {
+    ipcRenderer.on("transcription-segment", (event, segment) => callback(segment));
+  },
+  onStreamStarted: (callback) => {
+    ipcRenderer.on("stream-started", (event, data) => callback(data));
+  },
+  onStreamStopped: (callback) => {
+    ipcRenderer.on("stream-stopped", (event, data) => callback(data));
+  },
+
+  // === Legacy File-based APIs (fallback) ===
+  saveAudioFile: (arrayBuffer) => ipcRenderer.invoke("save-audio-file", arrayBuffer),
+  transcribeAudio: (filePath) => ipcRenderer.invoke("transcribe-audio", filePath),
+  onTranscriptionResult: (callback) => {
+    ipcRenderer.on("transcription-result", (event, text) => callback(text));
+  },
+});