feat: Add build scripts and runtime config support

Backend:
- Add setup-backend.sh/bat for one-click backend setup
- Fix test_auth.py mock settings (JWT_EXPIRE_HOURS)
- Fix test_excel_export.py TEMPLATE_DIR reference

Frontend:
- Add config.json for runtime API URL configuration
- Add init.js and settings.js for config loading
- Update main.js to load config from external file
- Update api.js to use dynamic API_BASE_URL
- Update all pages to initialize config before API calls
- Update package.json with extraResources for config

Build:
- Add build-client.sh/bat for packaging Electron + Sidecar
- Add build-all.ps1 PowerShell script with -ApiUrl parameter
- Add GitHub Actions workflow for Windows builds
- Add scripts/README.md documentation

This allows IT to configure backend URL without rebuilding.

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

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

backend/tests/test_excel_export.py

@@ -7,7 +7,11 @@ from openpyxl import load_workbook
 # Add parent directory to path
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-from app.routers.export import fill_template_workbook, create_default_workbook, TEMPLATE_DIR, RECORD_DIR
+from app.routers.export import fill_template_workbook, create_default_workbook, BASE_DIR
+from app.config import settings
+
+TEMPLATE_DIR = settings.get_template_dir(BASE_DIR)
+RECORD_DIR = settings.get_record_dir(BASE_DIR)
 
 
 def test_excel_export():