test(issue-5): phase 1 delegation characterization suite

The three lib.sh delegation helpers (delegate_submit_job,
delegate_publish_event, start_watchdog) had zero direct test coverage, so a
"full suite green" gate would have been vacuous for the Phase 1 extraction.
Add the regression oracle before the move:

- C-01..C-09 golden tests for the shell helpers: the non-fatal contract (empty
  job id, missing script, non-zero interpreter exit), exact argv forwarding,
  stdout-is-the-job-id-alone, and the daemon's PID/dedup/log-path behaviour.
  All are parametrized over MAM_DELEGATION_PY so the legacy and python bodies
  must agree.
- CLI contract snapshots taken from the argparse parsers rather than --help
  text, so wording stays free to change but option names, choices and defaults
  do not.
- Auto-completion invariant guards for the three surfaces that decide job
  status: EVENT_TO_STATUS, the wrapper's exit-code mapping, and reconcile.sh's
  terminal mutation literals.
- conftest: PV-2/PV-3 session guards asserting that every non-delegation
  lib_py.* module resolves to the real skills tree and that no temp-tree
  sys.path entry contributes a lib_py package. MAM_ENV_FILE is pointed at an
  absent file inside the sandbox so delegation code can never inject the real
  .mam.env into a test process.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UrDNJkHmm18uu7n7JwV5Qd

tests/fixtures/issue_5/phase1/help-job_subscriber.txt

@@ -0,0 +1,18 @@
+usage: job_subscriber.py [-h] (--job JOB | --wait-any) [--timeout TIMEOUT]
+                         [--idle-timeout IDLE_TIMEOUT] [--expect-retention]
+                         [--registry-dir REGISTRY_DIR] [-v]
+
+Subscribe to Job events on MQTT
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --job JOB             job id to watch
+  --wait-any            watch every pending/running job in the registry
+  --timeout TIMEOUT     wall-clock budget in seconds (default: job.timeout_sec
+                        or 3600)
+  --idle-timeout IDLE_TIMEOUT
+                        max seconds with no new event (default:
+                        job.idle_timeout_sec or 120)
+  --expect-retention    warn if no retained terminal event arrives promptly
+  --registry-dir REGISTRY_DIR
+  -v, --verbose