test: gate-tier AskUserQuestion floor tests for all plan-* review skills

Adds 4 finding-floor tests (one per plan-* skill) that catch the May
2026 transcript-bug class — model wrote a plan and called ExitPlanMode
without firing any review-phase AskUserQuestion. Asserts via
runPlanSkillFloorCheck that ANY non-permission AUQ render fires before
the agent reaches plan_ready.

Verified:
- Eng floor: passed in 59s
- CEO floor: passed in 197s
- Design floor: passed
- Devex floor: passed
- Total ~$2-6 per CI run; only triggers on diff against the 4 plan-*
  templates, the shared resolver review.ts, the seeds fixture, or the
  PTY runner helper.

Fixtures live in test/fixtures/forcing-finding-seeds.ts, one constant
per skill. Each seed is engineered to force at least one obvious
finding under that skill's review focus (architectural smell for eng,
scope-creep for ceo, UI-slop for design, painful onboarding for devex).

Touchfiles wiring:
- E2E_TOUCHFILES: 4 plan-*-finding-floor entries with deps on the
  matching skill template, the shared resolver, the seeds fixture,
  and the PTY runner helper
- E2E_TIERS: all 4 entries marked 'gate'
- touchfiles.test.ts: count assertion bumped 21→22 with explicit
  plan-ceo-finding-floor containment check

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/fixtures/forcing-finding-seeds.ts

@@ -0,0 +1,83 @@
+/**
+ * Per-skill draft-plan seeds engineered to surface at least one
+ * review-phase finding in the corresponding plan-* review skill.
+ *
+ * Used by gate-tier finding-floor tests
+ * (test/skill-e2e-plan-{eng,ceo,design,devex}-finding-floor.test.ts) as
+ * the minimum-cost regression for the May 2026 transcript bug:
+ *   "/plan-eng-review reviewed a real PR diff, wrote a multi-section
+ *    review plan to ~/.claude/plans/ and called ExitPlanMode without
+ *    ever firing AskUserQuestion."
+ *
+ * Each seed is small and pre-loaded with one obvious finding the
+ * matching skill cannot honestly miss. Floor tests assert
+ * `reviewCount >= 1` — i.e., the model fired at least one review-phase
+ * AUQ before reaching plan_ready / completion_summary / ceiling.
+ *
+ * Each seed includes the standard "write your plan-mode plan to /tmp/…"
+ * preamble that the existing periodic finding-count fixtures use, so
+ * the agent has a concrete plan-file target. The /tmp path is unique
+ * per skill to avoid collisions if floor tests run in parallel.
+ *
+ * For a deeper [N-1, N+2] count band assertion, see the periodic
+ * test/skill-e2e-plan-{X}-finding-count.test.ts fixtures.
+ */
+
+export const FORCING_FLOOR_ENG = [
+  'Please review this plan thoroughly. As you go, write your plan-mode plan to /tmp/gstack-test-plan-eng-floor.md (use Edit/Write to that exact path).',
+  '',
+  '# Plan: Add request-id propagation across services',
+  '',
+  '## Architecture',
+  "We'll roll a custom UUIDv7 generator inline in each service rather than",
+  "use Node's crypto.randomUUID() built-in. Same shape, but we want full",
+  'control over the entropy source for "future flexibility" — no concrete',
+  'reason yet.',
+].join('\n');
+
+export const FORCING_FLOOR_CEO = [
+  'Please review this plan thoroughly. As you go, write your plan-mode plan to /tmp/gstack-test-plan-ceo-floor.md (use Edit/Write to that exact path).',
+  '',
+  '# Plan: Launch a "developer-friendly" pricing tier',
+  '',
+  '## Goal',
+  'Increase developer adoption.',
+  '',
+  '## Success metric',
+  'More signups.',
+  '',
+  '## Premise',
+  "We haven't talked to any developers about whether the current pricing",
+  'is actually a barrier. The team agreed it "feels like" it should be cheaper.',
+].join('\n');
+
+export const FORCING_FLOOR_DESIGN = [
+  'Please review this plan thoroughly. As you go, write your plan-mode plan to /tmp/gstack-test-plan-design-floor.md (use Edit/Write to that exact path).',
+  '',
+  '# Plan: Marketing landing page',
+  '',
+  '## Layout',
+  'All headings, taglines, and body copy will be center-aligned for a',
+  '"clean modern look." The hero h1 sits 8px above the subhead with no',
+  'breathing room; the CTA button is the same visual weight as a',
+  'secondary "Learn more" link directly beside it.',
+].join('\n');
+
+export const FORCING_FLOOR_DEVEX = [
+  'Please review this plan thoroughly. As you go, write your plan-mode plan to /tmp/gstack-test-plan-devex-floor.md (use Edit/Write to that exact path).',
+  '',
+  '# Plan: SDK quickstart docs',
+  '',
+  '## Onboarding flow',
+  'Step 1: clone the repo.',
+  'Step 2: install bun manually if not present.',
+  'Step 3: copy .env.example to .env and fill in 8 environment variables.',
+  'Step 4: run database migrations against your local Postgres.',
+  'Step 5: start the dev server.',
+  'Step 6: open the docs in a separate tab.',
+  'Step 7: register an API key by emailing the team.',
+  'Step 8: paste the key into your .env, restart the server, then make',
+  'your first SDK call.',
+  '',
+  'No quickstart command, no hosted sandbox, no copy-pasteable curl example.',
+].join('\n');