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>

scripts/models.ts

@@ -13,6 +13,7 @@
 
 export const ALL_MODEL_NAMES = [
   'claude',
+  'opus-4-7',
   'gpt',
   'gpt-5.4',
   'gemini',
@@ -51,6 +52,7 @@ export function resolveModel(input: string): Model | null {
   if (/^gpt-5\.4(-|$)/.test(s)) return 'gpt-5.4';
   if (/^gpt(-|$)/.test(s)) return 'gpt';
   if (/^o[0-9]+(-|$)/.test(s)) return 'o-series';
+  if (/^claude-opus-4-7(-|$)/.test(s)) return 'opus-4-7';
   if (/^claude(-|$)/.test(s)) return 'claude';
   if (/^gemini(-|$)/.test(s)) return 'gemini';