feat: suppress healthcheck logs in dev mode

Reduce visual noise during development by logging healthcheck requests
at DEBUG level when DEPLOYMENT_MODE=DEV. Production mode continues to
log healthchecks at INFO level for proper observability.

Changes:
- Modified /health endpoint to check deployment mode
- DEV mode: logs at DEBUG level (only visible with DEBUG logging)
- PROD mode: logs at INFO level (maintains current behavior)

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

api/main.py

@@ -713,6 +713,14 @@ def create_app(
         Returns:
             Health status and timestamp
         """
+        from tools.deployment_config import is_dev_mode
+
+        # Log at DEBUG in dev mode, INFO in prod mode
+        if is_dev_mode():
+            logger.debug("Health check")
+        else:
+            logger.info("Health check")
+
         try:
             # Test database connection
             conn = get_db_connection(app.state.db_path)