fix: let HTTPException pass through @handle_db_errors unchanged

The decorator was catching all exceptions including intentional
HTTPException (401, 404, etc.) and re-wrapping them as 500 "Database
error". This masked auth failures and other deliberate HTTP errors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/dependencies.py

@@ -807,6 +807,10 @@ def handle_db_errors(func):
 
             return result
 
+        except HTTPException:
+            # Let intentional HTTP errors (401, 404, etc.) pass through unchanged
+            raise
+
         except Exception as e:
             elapsed_time = time.time() - start_time
             error_trace = traceback.format_exc()