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>

cron/scheduler.py

@@ -474,11 +474,11 @@ def run_job(job: dict) -> tuple[bool, str, str, Optional[str]]:
         if _session_db:
             try:
                 _session_db.end_session(_cron_session_id, "cron_complete")
-            except Exception as e:
+            except (Exception, KeyboardInterrupt) as e:
                 logger.debug("Job '%s': failed to end session: %s", job_id, e)
             try:
                 _session_db.close()
-            except Exception as e:
+            except (Exception, KeyboardInterrupt) as e:
                 logger.debug("Job '%s': failed to close SQLite session store: %s", job_id, e)