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_issue26_ints.py

@@ -83,8 +83,9 @@ INPUTS = ["30", "0700", "0900", " 30 ", "0", "-5", "abc", "", "1e3", "9999999999
 # arithmetic, each with where the value goes. B5 fails on any `${MAM_/SKS_/
 # DELEGATE_JOB_/RECONCILE_…:-<digit>…}` that is neither here nor normalised
 # through INT_KNOBS, so a new knob has to be classified to land.
+# Issue #17 item 4: MAM_DELEGATE_FAIL_CLOSED and MAM_STALL_WATCH are read by
+# lib_py/delegation/wrapper.py now, not by shell code.
 NOT_ARITHMETIC = {
-    "MAM_DELEGATE_FAIL_CLOSED": "string compare", "MAM_STALL_WATCH": "string compare",
     "MAM_ALLOW_UNSIGNED_DISPATCH": "string compare", "MAM_DELEGATE_JOB_NO_MAIN": "string compare",
     "MAM_NO_AUTOSTART": "string compare", "MAM_SHIM_DEBUG": "string compare",
     "MAM_NO_SUBSCRIBER_DAEMON": "string compare", "MAM_DELEGATION_PY": "string compare",