feat(issue-33): the job budget travels and the two clocks carry different labels

- wrapper: TIMEOUT falls back to MAM_JOB_TIMEOUT_S (--timeout > env > 3600);
  an invalid value warns and keeps 3600.
- loop: --job-timeout <sec> (run_loop.sh passes it on; refused in the legacy
  shell loop). The runner always hands the wrapper --timeout, so the budget
  the wrapper registers is the one its wait caps come from.
- runner: wait_for_job and the MAM_CHILD_WAIT_S default are budget + 300 s
  (MAM_WAIT_GRACE_S), today's 3900 with no option; an explicit
  MAM_CHILD_WAIT_S still wins.
- subscriber: the wall-clock budget returns 4 (RC_WALL_CLOCK), silence keeps
  2 (RC_NO_EVENT). The wrapper maps both to caller rc 2 and labels the close
  from the rc: wall_clock_timeout vs deadline_timeout; the disk-heartbeat
  grace that ends on the deadline is the wall clock too.
- registry close accepts wall_clock_timeout (engine: -> error); the remote
  runner's deadline and command-timeout details lead with wall_clock_timeout;
  the sub-job table files it CLOSED-UNCONFIRMED (first token, colon stripped).

Test expectations changed only where the contract changed: the loop's
contract_args now starts with --timeout, the subscriber's exit-code docstring
names rc 2/4, and the registry --help capture lists the new close kind.

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

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

@@ -11,7 +11,7 @@ positional arguments:
     get                 print one job record as JSON
     status              set a job status
     update              update a job record
-    close               close a job with deadline_timeout or cancelled
+    close               close a job with deadline_timeout, wall_clock_timeout or cancelled
     get-feedback        get the last feedback detail (completed/error) for a
                         job
     pick                claim a pending job for a session; prints id