feat: implement missing API endpoints for scheduler, logging, and diagnostics

- Add scheduler API endpoints for configuration and manual rescan triggers
- Add logging API endpoints for config management and log file operations
- Add diagnostics API endpoints for network and system information
- Extend config API with advanced settings, directory updates, export, and reset
- Update FastAPI app to include new routers
- Update API reference documentation with all new endpoints
- Update infrastructure documentation with endpoint listings
- Add comprehensive API implementation summary

All new endpoints follow project coding standards with:
- Type hints and Pydantic validation
- Proper authentication and authorization
- Comprehensive error handling and logging
- Security best practices (path validation, input sanitization)

Test results: 752/802 tests passing (93.8%)

src/server/fastapi_app.py

@@ -22,7 +22,10 @@ from src.server.api.analytics import router as analytics_router
 from src.server.api.anime import router as anime_router
 from src.server.api.auth import router as auth_router
 from src.server.api.config import router as config_router
+from src.server.api.diagnostics import router as diagnostics_router
 from src.server.api.download import router as download_router
+from src.server.api.logging import router as logging_router
+from src.server.api.scheduler import router as scheduler_router
 from src.server.api.websocket import router as websocket_router
 from src.server.controllers.error_controller import (
     not_found_handler,
@@ -130,6 +133,9 @@ app.include_router(health_router)
 app.include_router(page_router)
 app.include_router(auth_router)
 app.include_router(config_router)
+app.include_router(scheduler_router)
+app.include_router(logging_router)
+app.include_router(diagnostics_router)
 app.include_router(analytics_router)
 app.include_router(anime_router)
 app.include_router(download_router)