Split /create-epics-stories into /create-epics + /create-stories; add /dev-story

- NEW /create-epics (agent: technical-director): architect-level epic scoping,
  one epic per architectural module. Does not create stories.
- NEW /create-stories (agent: lead-programmer): decomposes a single epic into
  story files with embedded TR-IDs, ADR guidance, and test evidence paths.
- NEW /dev-story: the missing implementation skill — reads a story, loads full
  context (TR registry, ADR, control manifest, engine prefs), routes to the
  correct programmer agent via Task, and drives implementation to completion
  including writing the test.
- DEPRECATED /create-epics-stories: added redirect notice; original content
  preserved for reference.
- Updated /gate-check: Pre-Prod→Production artifact check and follow-up actions
  now reference the two new skills.
- Updated workflow-catalog.yaml: replaced create-epics-stories step with two
  separate steps; implement step now references /dev-story with command field.

Story loop is now explicit:
  /story-readiness → /dev-story → /code-review → /story-done

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/gate-check/SKILL.md

@@ -121,9 +121,10 @@ The project progresses through these stages:
 - [ ] At least 3 ADRs covering Foundation-layer decisions exist in `docs/architecture/`
 - [ ] Control manifest exists at `docs/architecture/control-manifest.md`
       (generated by `/create-control-manifest` from Accepted ADRs)
-- [ ] Epics and stories defined in `production/epics/` with at least Foundation
-      and Core layer epics present (use `/create-epics-stories layer: foundation`
-      and `/create-epics-stories layer: core` to create them)
+- [ ] Epics defined in `production/epics/` with at least Foundation and Core
+      layer epics present (use `/create-epics layer: foundation` and
+      `/create-epics layer: core` to create them, then `/create-stories [epic-slug]`
+      for each epic)
 - [ ] Vertical Slice build exists and is playable (not just scope-defined)
 - [ ] Vertical Slice has been playtested with at least 3 sessions (internal OK)
 - [ ] Vertical Slice playtest report exists at `production/playtests/` or equivalent
@@ -320,7 +321,8 @@ Based on the verdict, suggest specific next steps:
 - **ADRs missing engine compatibility sections?** → Re-run `/architecture-decision`
   or manually add Engine Compatibility sections to existing ADRs
 - **Missing control manifest?** → `/create-control-manifest` (requires Accepted ADRs)
-- **Missing epics/stories?** → `/create-epics-stories all` (requires control manifest)
+- **Missing epics?** → `/create-epics layer: foundation` then `/create-epics layer: core` (requires control manifest)
+- **Missing stories for an epic?** → `/create-stories [epic-slug]` (run after each epic is created)
 - **Stories not implementation-ready?** → `/story-readiness` to validate stories before developers pick them up
 - **Tests failing?** → delegate to `lead-programmer` or `qa-tester`
 - **No playtest data?** → `/playtest-report`