feat: Add embedded backend packaging for all-in-one deployment

- Add backend/run_server.py entry point for embedded deployment
- Add backend/build.py PyInstaller script for backend packaging
- Modify config.py to support frozen executable paths
- Extend client/config.json with backend configuration section
- Add backend sidecar management in Electron main process
- Add Whisper model download progress reporting
- Update build-client.bat with --embedded-backend flag
- Update DEPLOYMENT.md with all-in-one deployment documentation

This enables packaging frontend and backend into a single executable
for simplified enterprise deployment. Backward compatible with
existing separate deployment mode (backend.embedded: false).

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

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

backend/build.py

@@ -0,0 +1,112 @@
+#!/usr/bin/env python3
+"""
+Build script for creating standalone backend executable using PyInstaller.
+Uses --onedir mode for faster startup compared to --onefile.
+"""
+
+import subprocess
+import sys
+import os
+import shutil
+
+
+def build():
+    """Build the backend executable."""
+    script_dir = os.path.dirname(os.path.abspath(__file__))
+
+    # PyInstaller command with --onedir for faster startup
+    cmd = [
+        sys.executable, "-m", "PyInstaller",
+        "--onedir",
+        "--name", "backend",
+        "--distpath", "dist",
+        "--workpath", "build",
+        "--specpath", "build",
+        # FastAPI and web framework
+        "--hidden-import", "uvicorn",
+        "--hidden-import", "uvicorn.logging",
+        "--hidden-import", "uvicorn.loops",
+        "--hidden-import", "uvicorn.loops.auto",
+        "--hidden-import", "uvicorn.protocols",
+        "--hidden-import", "uvicorn.protocols.http",
+        "--hidden-import", "uvicorn.protocols.http.auto",
+        "--hidden-import", "uvicorn.protocols.websockets",
+        "--hidden-import", "uvicorn.protocols.websockets.auto",
+        "--hidden-import", "uvicorn.lifespan",
+        "--hidden-import", "uvicorn.lifespan.on",
+        "--hidden-import", "uvicorn.lifespan.off",
+        "--hidden-import", "fastapi",
+        "--hidden-import", "starlette",
+        "--hidden-import", "pydantic",
+        "--hidden-import", "pydantic_core",
+        # Database
+        "--hidden-import", "mysql.connector",
+        "--hidden-import", "mysql.connector.pooling",
+        # HTTP client
+        "--hidden-import", "httpx",
+        "--hidden-import", "httpcore",
+        # Authentication
+        "--hidden-import", "jose",
+        "--hidden-import", "jose.jwt",
+        "--hidden-import", "cryptography",
+        # Excel export
+        "--hidden-import", "openpyxl",
+        # Multipart form handling
+        "--hidden-import", "multipart",
+        "--hidden-import", "python_multipart",
+        # Environment loading
+        "--hidden-import", "dotenv",
+        # Application modules
+        "--hidden-import", "app",
+        "--hidden-import", "app.main",
+        "--hidden-import", "app.config",
+        "--hidden-import", "app.database",
+        "--hidden-import", "app.auth",
+        "--hidden-import", "app.routers",
+        "--hidden-import", "app.routers.auth",
+        "--hidden-import", "app.routers.meetings",
+        "--hidden-import", "app.routers.dify",
+        "--hidden-import", "app.routers.health",
+        "--hidden-import", "app.routers.excel",
+        # Collect package data
+        "--collect-data", "pydantic",
+        "--collect-data", "uvicorn",
+        "run_server.py"
+    ]
+
+    print("Building backend executable...")
+    print(f"Command: {' '.join(cmd)}")
+
+    result = subprocess.run(cmd, cwd=script_dir)
+
+    if result.returncode != 0:
+        print("\nBuild failed!")
+        sys.exit(1)
+
+    # Copy template directory to dist
+    template_src = os.path.join(script_dir, "template")
+    template_dst = os.path.join(script_dir, "dist", "backend", "template")
+
+    if os.path.exists(template_src):
+        print(f"\nCopying template directory to {template_dst}...")
+        if os.path.exists(template_dst):
+            shutil.rmtree(template_dst)
+        shutil.copytree(template_src, template_dst)
+        print("Template directory copied successfully.")
+    else:
+        print(f"\nWarning: Template directory not found at {template_src}")
+
+    # Create empty record directory
+    record_dst = os.path.join(script_dir, "dist", "backend", "record")
+    os.makedirs(record_dst, exist_ok=True)
+    print(f"Created record directory at {record_dst}")
+
+    print("\nBuild successful!")
+    print(f"Executable created at: dist/backend/backend.exe (Windows) or dist/backend/backend (Linux)")
+    print("\nTo run:")
+    print("  1. Copy config.json to dist/backend/")
+    print("  2. Run: dist/backend/backend.exe (Windows) or ./dist/backend/backend (Linux)")
+
+
+if __name__ == "__main__":
+    build()