refactor(opus-4.7): split overlay, align routing, fix trailer fallback

Follow-up to wintermute's initial Opus 4.7 migration commit (addresses
ship-quality review findings before v1.6.1.0 release).

Overlay split (model-overlays/):
  - Move 4 Opus-4.7-specific nudges (Fan out, Effort-match, Batch your
    questions, Literal interpretation) from claude.md into new
    opus-4-7.md with {{INHERIT:claude}}
  - claude.md now holds only model-agnostic nudges (Todo discipline,
    Think before heavy, Dedicated tools over Bash)
  - Prevents Opus-4.7-specific guidance leaking onto Sonnet/Haiku
  - Uses existing {{INHERIT:claude}} mechanism at
    scripts/resolvers/model-overlay.ts:28-43

scripts/models.ts:
  - Add opus-4-7 to ALL_MODEL_NAMES
  - resolveModel: claude-opus-4-7-* variants route to opus-4-7,
    all other claude-* variants continue to route to claude

scripts/resolvers/utility.ts:
  - Update coAuthor trailer fallback: Opus 4.6 -> Opus 4.7
    (fallback was missed in the initial migration commit)

scripts/resolvers/preamble/generate-routing-injection.ts:
  - Align policy with new SKILL.md.tmpl: soft "when in doubt, invoke"
    instead of hard "ALWAYS invoke... Do NOT answer directly"
  - Replace stale /checkpoint reference with /context-save +
    /context-restore (skills were renamed in v1.0.1.0)
  - Expand route coverage to match full skill inventory:
    /plan-devex-review, /qa-only, /devex-review, /land-and-deploy,
    /setup-deploy, /canary, /open-gstack-browser,
    /setup-browser-cookies, /benchmark, /learn, /plan-tune, /health

scripts/resolvers/preamble/generate-voice-directive.ts:
  - Voice example closing: "Want me to ship it?" -> "Want me to fix it?"
  - Preserves directness while routing through review gates

SKILL.md.tmpl:
  - Add routing triggers for skills that were missing from the list:
    /plan-devex-review, /qa-only, /devex-review, /land-and-deploy,
    /setup-deploy, /canary, /open-gstack-browser,
    /setup-browser-cookies, /benchmark, /learn, /plan-tune, /health
  - Within Opus 4.7 overlay, added scope boundary to
    "Literal interpretation" nudge ("fix tests that this branch
    introduced or is responsible for")
  - Added pacing exception to "Batch your questions" nudge so skills
    that require one-question-at-a-time pacing still win

Follow-up commit will regenerate SKILL.md files + update goldens.

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

SKILL.md.tmpl

@@ -36,12 +36,18 @@ quality gates that produce better results than answering inline.
 - User asks to review architecture, lock in the plan, "does this design make sense" → invoke `/plan-eng-review`
 - User asks about design system, brand, visual identity, "how should this look" → invoke `/design-consultation`
 - User asks to review design of a plan → invoke `/plan-design-review`
+- User asks about developer experience of a plan, API/CLI/SDK design → invoke `/plan-devex-review`
 - User wants all reviews done automatically, "review everything" → invoke `/autoplan`
 - User reports a bug, error, broken behavior, "why is this broken", "this doesn't work", "wtf", "something's wrong" → invoke `/investigate`
 - User asks to test the site, find bugs, QA, "does this work", "check the deploy" → invoke `/qa`
+- User asks to just report bugs without fixing → invoke `/qa-only`
 - User asks to review code, check the diff, pre-landing review, "look at my changes" → invoke `/review`
 - User asks about visual polish, design audit of a live site, "this looks off" → invoke `/design-review`
+- User asks to audit the live developer experience, time-to-hello-world → invoke `/devex-review`
 - User asks to ship, deploy, push, create a PR, "let's land this", "send it" → invoke `/ship`
+- User asks to merge + deploy + verify as one flow → invoke `/land-and-deploy`
+- User asks to configure deployment for the project → invoke `/setup-deploy`
+- User asks to monitor prod after shipping, post-deploy checks → invoke `/canary`
 - User asks to update docs after shipping → invoke `/document-release`
 - User asks for a weekly retro, what did we ship, "how'd we do" → invoke `/retro`
 - User asks for a second opinion, codex review → invoke `/codex`
@@ -52,6 +58,12 @@ quality gates that produce better results than answering inline.
 - User asks to resume, restore, "where was I" → invoke `/context-restore`
 - User asks about security, OWASP, vulnerabilities, "is this secure" → invoke `/cso`
 - User asks to make a PDF, document, publication → invoke `/make-pdf`
+- User asks to launch a real browser for QA, "open the browser" → invoke `/open-gstack-browser`
+- User asks to import cookies for authenticated testing → invoke `/setup-browser-cookies`
+- User asks about page speed, performance regression, benchmarks → invoke `/benchmark`
+- User asks what gstack has learned, "show learnings" → invoke `/learn`
+- User asks to tune question sensitivity, "stop asking me that" → invoke `/plan-tune`
+- User asks for code quality dashboard, "health check" → invoke `/health`
 
 **When in doubt, invoke the skill.** A false positive (invoking a skill that wasn't
 needed) is cheaper than a false negative (answering ad-hoc when a structured workflow