chore(refactor): Improve conversation permission filtering (#11166)

1. Add permission filter service to separate permission filtering logic
from conversation queries
2. Implement hierarchical permissions with cleaner logic:
   - conversation_manage gives access to all conversations
- conversation_unassigned_manage gives access to unassigned and user's
conversations
- conversation_participating_manage gives access only to user's
conversations

---------

Co-authored-by: Pranav <pranav@chatwoot.com>

.gitignore

@@ -91,3 +91,6 @@ yarn-debug.log*
 # Vite uses dotenv and suggests to ignore local-only env files. See
 # https://vitejs.dev/guide/env-and-mode.html#env-files
 *.local
+
+# Claude.ai config file
+CLAUDE.md