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/api/scheduler.py

@@ -0,0 +1,130 @@
+"""Scheduler API endpoints for Aniworld.
+
+This module provides endpoints for managing scheduled tasks such as
+automatic anime library rescans.
+"""
+import logging
+from typing import Dict, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+
+from src.server.models.config import SchedulerConfig
+from src.server.services.config_service import ConfigServiceError, get_config_service
+from src.server.utils.dependencies import require_auth
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/api/scheduler", tags=["scheduler"])
+
+
+@router.get("/config", response_model=SchedulerConfig)
+def get_scheduler_config(
+    auth: Optional[dict] = Depends(require_auth)
+) -> SchedulerConfig:
+    """Get current scheduler configuration.
+
+    Args:
+        auth: Authentication token (optional for read operations)
+
+    Returns:
+        SchedulerConfig: Current scheduler configuration
+
+    Raises:
+        HTTPException: If configuration cannot be loaded
+    """
+    try:
+        config_service = get_config_service()
+        app_config = config_service.load_config()
+        return app_config.scheduler
+    except ConfigServiceError as e:
+        logger.error(f"Failed to load scheduler config: {e}")
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail=f"Failed to load scheduler configuration: {e}",
+        ) from e
+
+
+@router.post("/config", response_model=SchedulerConfig)
+def update_scheduler_config(
+    scheduler_config: SchedulerConfig,
+    auth: dict = Depends(require_auth),
+) -> SchedulerConfig:
+    """Update scheduler configuration.
+
+    Args:
+        scheduler_config: New scheduler configuration
+        auth: Authentication token (required)
+
+    Returns:
+        SchedulerConfig: Updated scheduler configuration
+
+    Raises:
+        HTTPException: If configuration update fails
+    """
+    try:
+        config_service = get_config_service()
+        app_config = config_service.load_config()
+
+        # Update scheduler section
+        app_config.scheduler = scheduler_config
+
+        # Save and return
+        config_service.save_config(app_config)
+        logger.info(
+            f"Scheduler config updated by {auth.get('username', 'unknown')}"
+        )
+
+        return scheduler_config
+    except ConfigServiceError as e:
+        logger.error(f"Failed to update scheduler config: {e}")
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail=f"Failed to update scheduler configuration: {e}",
+        ) from e
+
+
+@router.post("/trigger-rescan", response_model=Dict[str, str])
+async def trigger_rescan(auth: dict = Depends(require_auth)) -> Dict[str, str]:
+    """Manually trigger a library rescan.
+
+    This endpoint triggers an immediate anime library rescan, bypassing
+    the scheduler interval.
+
+    Args:
+        auth: Authentication token (required)
+
+    Returns:
+        Dict with success message
+
+    Raises:
+        HTTPException: If rescan cannot be triggered
+    """
+    try:
+        # Import here to avoid circular dependency
+        from src.server.fastapi_app import get_series_app
+
+        series_app = get_series_app()
+        if not series_app:
+            raise HTTPException(
+                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+                detail="SeriesApp not initialized",
+            )
+
+        # Trigger the rescan
+        logger.info(
+            f"Manual rescan triggered by {auth.get('username', 'unknown')}"
+        )
+
+        # Use existing rescan logic from anime API
+        from src.server.api.anime import trigger_rescan as do_rescan
+
+        return await do_rescan()
+
+    except HTTPException:
+        raise
+    except Exception as e:
+        logger.exception("Failed to trigger manual rescan")
+        raise HTTPException(
+            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+            detail=f"Failed to trigger rescan: {str(e)}",
+        ) from e