feat(config): T-1278 — the jobs domain, and typer.Exit is not a SystemExit

reach jobs list / status / log --follow / wait. A domain rather than core/,
because these verbs carry logic and state: they reconcile recorded status
against process liveness, tail a file from an offset, and relay an exit code.

Found a latent bug in already-committed code before building on it. typer.Exit
is a RuntimeError, not a SystemExit, so @handle_errors caught it like any other
unexpected exception: `raise typer.Exit(3)` inside a decorated command printed
"unexpected Exit: 3" and exited 1, silently discarding the requested code.
Nothing hit it because the check router had been converted to ReachError — but
jobs wait needs exactly this and it is what anyone would naturally write. Added
core/errors.ReachExit as the sanctioned control-flow exit, passed straight
through with no verdict. ReachError would have been wrong twice: a failure
verdict for a command that worked, and a demand for a fix= where there is no
remedy.

Reconciliation proved out on a real corpse rather than a simulated one — the
job stranded by the T-1277 bug, status "running" with its process long gone,
now reports as died. DIED is derived, never recorded, because a process killed
outright cannot write its own ending. It relays 137, never 0: a died job has no
exit code of its own and borrowing success points the exit-0 trap straight at
whatever gated on the run.

Second UTC bug of the same family as T-1276's: jobs list reported a job started
minutes earlier as running for 133m, because _parse used mktime on a UTC stamp
and silently added the offset to every duration.

console.render() is public now, so jobs log replays stored events through the
same path a live run prints them — a second renderer would drift, and the
divergence would surface exactly when someone is reading a log to find out what
went wrong.

test_jobs.py closes the gap T-1257 named: D-263 claims services are callable
without a CLI round trip, and nothing had ever demonstrated it, which left the
layering as unverified decoration. Every test here calls the service directly.

Not yet exercised, and said plainly: log --follow against a genuinely
long-running job. Nothing in reach runs long enough to tail yet. The offset
mechanics underneath are tested; the live loop waits for a slow domain.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Makefile

@@ -307,6 +307,10 @@ test-tooling:
 	@mkdir -p .cache
 	@$(VENV_PY) tooling/test_lazy_domains.py 2> .cache/test-tooling-lazy-domains.log || \
 		{ echo "  FAIL: reach lazy registration — log follows:"; cat .cache/test-tooling-lazy-domains.log; exit 1; }
+	@echo "  [test-tooling] reach jobs service units (T-1278)..."
+	@mkdir -p .cache
+	@$(VENV_PY) tooling/test_jobs.py 2> .cache/test-tooling-jobs.log || \
+		{ echo "  FAIL: jobs service — log follows:"; cat .cache/test-tooling-jobs.log; exit 1; }
 	@echo "  [test-tooling] reach D-263 conformance (T-1270)..."
 	@mkdir -p .cache
 	@$(VENV_PY) tooling/test_conformance.py 2> .cache/test-tooling-conformance.log || \