feat: Add granular feature status stages across all skills

Replaces ambiguous 4-status system with 6 clear stages, one per skill:
Planned → Architected → In Progress → In Review → Approved → Deployed

- architecture: sets "Architected" (was "In Progress")
- frontend + backend: explicitly set "In Progress" with checklist items
- qa: sets "In Review" on start, "Approved" on pass (was only "In Review")
- general rules + INDEX.md: updated valid statuses and descriptions

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

.claude/skills/architecture/SKILL.md

@@ -90,7 +90,7 @@ Add a "Tech Design (Solution Architect)" section to `/features/PROJ-X.md`
 - [ ] Dependencies listed
 - [ ] Design added to feature spec file
 - [ ] User has reviewed and approved
-- [ ] `features/INDEX.md` status updated to "In Progress"
+- [ ] `features/INDEX.md` status updated to "Architected"
 
 ## Handoff
 After approval, tell the user: