fix(aipass): surface module errors instead of masking as 'Unknown command'

route_command swallowed any handle_command exception and let main() print
a misleading 'Unknown command', hiding real failures (e.g. the Windows
aipass-init error the e2e harness hit). It now also prints the failing
module + traceback to stderr. Bool contract unchanged; 24/24 aipass unit
tests pass. This makes the masked Windows init failure diagnosable.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/aipass/aipass/apps/aipass.py

@@ -17,6 +17,7 @@ Auto-discovery architecture:
 
 import sys
 import importlib
+import traceback
 from pathlib import Path
 from typing import List, Any
 
@@ -59,7 +60,12 @@ def route_command(command: str, args: List[str], modules: List[Any]) -> bool:
             if module.handle_command(command, args):
                 return True
         except Exception as e:
+            # A module that owns this command but fails must not be masked as
+            # "Unknown command" — surface the real error (and traceback) to
+            # stderr so failures are diagnosable instead of silently swallowed.
             logger.error(f"[AIPASS] Module {module.__name__} error: {e}")
+            print(f"[AIPASS] {module.__name__.split('.')[-1]} failed: {e}", file=sys.stderr)
+            traceback.print_exc(file=sys.stderr)
     return False