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/rules/general.md

@@ -48,7 +48,13 @@ After completing work on any feature, you MUST update tracking files. Follow thi
 
 **What to update in `features/INDEX.md`:**
 - Feature status column must match the feature spec header
-- Valid statuses: Planned, In Progress, In Review, Deployed
+- Valid statuses: Planned → Architected → In Progress → In Review → Approved → Deployed
+  - **Planned**: after `/requirements`
+  - **Architected**: after `/architecture`
+  - **In Progress**: after `/frontend` or `/backend` starts
+  - **In Review**: after `/qa` starts
+  - **Approved**: after `/qa` passes (no critical/high bugs)
+  - **Deployed**: after `/deploy`
 
 **NEVER do this:**
 - Do NOT say "I've updated the feature spec" without actually calling the Edit tool