fix: properly clean up thinking task on CTRL-C

Fixes issue where pressing CTRL-C during agent processing would not
exit cleanly. The thinking indicator task was not being cancelled
because KeyboardInterrupt doesn't inherit from Exception.

Problem:
- KeyboardInterrupt inherits from BaseException, not Exception
- The `except Exception as e:` block didn't catch KeyboardInterrupt
- Thinking task kept running in background after CTRL-C
- Process appeared to hang or not exit fully

Solution:
- Added `finally` block to _stream_agent_response()
- Always cancels and awaits the thinking task cleanup
- Properly handles CancelledError from task cancellation
- Ensures clean exit even when interrupted

Testing: All 273 tests passing

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

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

Author: jwesleye

src/basic_agent_chat_loop/chat_loop.py

@@ -935,11 +935,6 @@ async def _stream_agent_response(self, query: str) -> Dict[str, Any]:
             return {"duration": duration, "usage": usage_info}
 
         except Exception as e:
-            # Cleanup thinking indicator on error
-            stop_thinking.set()
-            if thinking_task and not thinking_task.done():
-                await thinking_task
-
             duration = time.time() - start_time
             print(f"\n{Colors.DIM}{'-' * 60}{Colors.RESET}")
             print(Colors.error(f"{self.agent_name}: Query failed - {e}"))
@@ -954,6 +949,16 @@ async def _stream_agent_response(self, query: str) -> Dict[str, Any]:
 
             return {"duration": duration, "usage": None}
 
+        finally:
+            # Always cleanup thinking indicator, even on KeyboardInterrupt
+            stop_thinking.set()
+            if thinking_task and not thinking_task.done():
+                thinking_task.cancel()
+                try:
+                    await thinking_task
+                except asyncio.CancelledError:
+                    pass  # Expected when cancelling
+
     async def process_query(self, query: str):
         """Process query through agent with streaming and error recovery."""
         for attempt in range(1, self.max_retries + 1):