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/fake_python.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# Stub interpreter used by the Phase 1 characterization tests.
+# Records argv (one invocation per line) and replays a configured stdout/exit code.
+if [ -n "${STUB_ARGV_LOG:-}" ]; then
+  printf '%s\n' "$*" >> "$STUB_ARGV_LOG"
+fi
+if [ -n "${STUB_STDOUT:-}" ]; then
+  printf '%s\n' "$STUB_STDOUT"
+fi
+exit "${STUB_EXIT:-0}"

tests/fixtures/issue_5/phase1/fake_reconcile.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+# Stub monitor used by the Phase 1 watchdog characterization tests.
+# Sleeps so the spawned PID stays observable; never touches the registry.
+echo "fake reconcile started: $*"
+sleep 60

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

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

@@ -0,0 +1,22 @@
+usage: publish_event.py [-h] (--job JOB | --pick-pending)
+                        [--agent-session AGENT_SESSION]
+                        [--event {started,permission_required,progress,completed,error,cancelled}]
+                        [--detail DETAIL] [--data DATA] [--retained]
+                        [--registry-dir REGISTRY_DIR] [--attempts ATTEMPTS]
+                        [-v]
+
+Publish a Job event to MQTT
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --job JOB             job id to publish for
+  --pick-pending        auto-select a pending job for --agent-session
+  --agent-session AGENT_SESSION
+                        session label used with --pick-pending
+  --event {started,permission_required,progress,completed,error,cancelled}
+  --detail DETAIL
+  --data DATA           optional JSON object string
+  --retained            force retain=True (auto for completed/error)
+  --registry-dir REGISTRY_DIR
+  --attempts ATTEMPTS
+  -v, --verbose

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

@@ -0,0 +1,22 @@
+usage: registry.py [-h] [--registry-dir REGISTRY_DIR]
+                   {register,list,get,status,update,get-feedback,pick,logs}
+                   ...
+
+multi-agent-mux-delegate-job registry CLI
+
+positional arguments:
+  {register,list,get,status,update,get-feedback,pick,logs}
+    register            create a pending job; prints the job id
+    list                list jobs (optionally by status)
+    get                 print one job record as JSON
+    status              set a job status
+    update              update a job record
+    get-feedback        get the last feedback detail (completed/error) for a
+                        job
+    pick                claim a pending job for a session; prints id
+    logs                show the persistent audit log for a job, or --list
+                        every logged job
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --registry-dir REGISTRY_DIR