fix: catch KeyboardInterrupt in exit cleanup handlers (#3257)

except Exception does not catch KeyboardInterrupt (inherits from
BaseException). A second Ctrl+C during exit cleanup aborts pending
writes — Honcho observations dropped, SQLite sessions left unclosed,
cron job sessions never marked ended.

Changed to except (Exception, KeyboardInterrupt) at all five sites:
- cli.py: honcho.shutdown() and end_session() in finally exit block
- run_agent.py: _flush_honcho_on_exit atexit handler
- cron/scheduler.py: end_session() and close() in job finally block

Tests exercise the actual production code paths and confirm
KeyboardInterrupt propagates without the fix.

Co-authored-by: dieutx <dangtc94@gmail.com>

run_agent.py

@@ -2274,7 +2274,7 @@ class AIAgent:
                 return
             try:
                 manager.flush_all()
-            except Exception as exc:
+            except (Exception, KeyboardInterrupt) as exc:
                 logger.debug("Honcho flush on exit failed (non-fatal): %s", exc)
 
         atexit.register(_flush_honcho_on_exit)