fix: resolve type checking warnings for CI

- Add type casts for Starlette app state access
- Add assertions for cipher, card, board, stack after initialization
- Add None checks for XML element text attributes
- Handle __package__ being None in tracing setup
- Fix TokenBrokerService initialization to use storage credentials

Resolves 42 type warnings from ty-check, enabling CI linting to pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

nextcloud_mcp_server/observability/tracing.py

@@ -53,10 +53,11 @@ def setup_tracing(
     global _tracer
 
     # Create resource with service name
+    pkg_name = __package__.split(".")[0] if __package__ else "nextcloud_mcp_server"
     resource = Resource.create(
         {
             "service.name": service_name,
-            "service.version": version(__package__.split(".")[0]),
+            "service.version": version(pkg_name),
         }
     )