refactor(issue-17): item 4 - the delegate-job wrapper's decisions move to Python

The wrapper keeps spawn / wait / kill, key injection and the herdr
diagnostic probe; what it decided in bash is now lib_py/delegation/wrapper.py,
reached through one `_decide` helper:

- finalize_unfinished: the clock choice, the disk grace and broker
  re-observation, the close request / label, the close and the event
  (finalize-begin / finalize-end; bash runs only the busy probe between them)
- start_stall_watch: whether to watch (MAM_STALL_WATCH, remote, human)
- _map_sub_rc, _rc_for (+ MAM_DELEGATE_FAIL_CLOSED), the subscriber
  early-exit check and cmd_wait's rc normalisation
- mam_int / mam_int_knob run lib_py/ints.py, which is also the runner's
  _positive_int: one implementation of the Issue #26 rule

No behaviour change: tests/test_issue17_item4_decisions.py runs the old
bash functions (copied verbatim from 7209750) and the new wrapper on the
same inputs and compares output, FINAL_JOB_STATUS and the registry /
publish calls. Three static tests that pinned the old bash literals now
pin the Python entry points instead.

Refs #17

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_tier1_unit.py

@@ -841,11 +841,16 @@ def test_g9_subscriber_broker_down_no_disk_terminal_exits_3(mam_sandbox, monkeyp
 
 
 def test_g10_delegate_job_rc3_not_mistaken_for_error(mam_sandbox):
-    """G-10: multi-agent-mux-delegate-job maps rc=3 to broker_unavailable and checks disk status."""
+    """G-10: multi-agent-mux-delegate-job maps rc=3 to broker_unavailable and checks disk status.
+    Issue #17 item 4: the mapping is lib_py/delegation/wrapper.py's sub_status."""
     delegate_script = mam_sandbox / "skills" / "multi-agent-mux-delegate-job" / "multi-agent-mux-delegate-job"
-    content = delegate_script.read_text()
-    assert "elif [[ $sub_rc -eq $SUB_RC_BROKER_UNAVAILABLE ]]; then" in content
-    assert 'job_status="broker_unavailable"' in content
+    assert '_decide sub-status "$sub_rc"' in delegate_script.read_text()
+    from lib_py.delegation import wrapper
+    reg = mam_sandbox / "g10-reg"
+    reg.mkdir()
+    assert wrapper.sub_status(3, str(reg), "g10") == "broker_unavailable"
+    (reg / "g10.json").write_text('{"status": "completed"}')
+    assert wrapper.sub_status(3, str(reg), "g10") == "completed"
 
 
 def test_claude_adapter_ready_tokens_includes_modern_banners():