fix(#4682): route stale verification to the verifier regeneration path (#4818)

* test(#4682): add failing-first coverage for stale verification routing

* fix(#4682): route stale verification to the verifier regeneration path

The stale routing entry sent users to /gsd-verify-work — but verify-work
never rewrites VERIFICATION.md (its only write is the human_needed
canonicalization), so following the advice re-ran UAT, reached the same
stale check, and looped. init's projector and execute-phase's generic
next_command presentation both mirror this entry, so the dead end appeared
on three surfaces.

The stale entry now routes to execute-phase, and execute-phase's
all-plans-complete resume tree gains a stale arm (as a steps/ part, keeping
the spine under its frozen ADR-857 ceiling) mirroring the missing route:
skip cross_ai_delegation/execute_waves/checkpoint_handling, continue at
aggregate_results, and let verify_phase_goal re-dispatch the gsd-verifier —
regenerating VERIFICATION.md and its digest, marked phase or not. The
non-stale fall-through. Staleness detection, the digest format (#4623),
every other routing entry, and the #3684 resume arms are untouched.

Emitted-Drift-Ack-Growth: verify-work.md — stale stop rewritten to dispatch the verifier and re-check (#4682)
Emitted-Drift-Ack-Growth: execute-phase.md — VERIFY_STATUS == stale resume arm added to condition 3 (#4682)

* test(#4682): register the stale-reverification part and align projected commands

The new steps/ part must be registered in the inventory manifest and the
per-runtime golden install trees (regen:derived); the projected stale
next_command is /gsd-execute-phase <phase> (formatGsdSlash prefixes the
runtime surface), the human_needed bare-report probe keeps routing to
verify-work (unchanged semantics), and init-manager's recommended action
follows the new command.

* test(#4682): prefix the remaining stale routing assertions with the runtime surface

Nine stale next_command assertions and the human_needed bare-report probe
still carried the unprefixed or flipped forms from the earlier line-number
edit; all now assert the shipped /gsd-execute-phase <phase> projection,
with the human_needed probe reverted to its unchanged verify-work routing.

* test(#4682): align the last stale projection assertions with the execute-phase route

* docs(#4682): backfill changeset PR number

* test(#4682): refresh the compact-content baseline after the rebase

The rebase onto the #4670 squash brought verify-work.md's bounded
reconciliation text into this branch; the committed compact-content
baseline now reflects the post-rebase split sizes. Local --check is
clean; the previous bench drift (+243) was the baseline, not the diff.

* fix(#4682): carry the response_language directive in the stale-reverification part

The new steps/ part is its own coverage unit for lint-response-language-coverage;
it takes the shared canonical directive line like its sibling execute-phase
parts.

---------

Co-authored-by: sim <sim@local>

.changeset/vivid-deer-howl.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 4818
+---
+**Stale verification now routes to the verifier** — the `stale` status told users to re-run `/gsd-verify-work`, but that workflow never rewrites VERIFICATION.md, so following the advice looped forever. The routing now names the regeneration path (execute-phase resumes at the verification gates and re-runs the verifier), and verify-work's stale stop dispatches `gsd-verifier` and re-checks instead of self-referencing. (#4682)