refactor: Migrate to Git-based workflow (v1.4.0)

BREAKING CHANGE: Removed FEATURE_CHANGELOG.md and test-reports/

**What changed:**
- All 6 agents now use Git commands to check existing features/components
- Feature specs include test results and deployment status (no separate files)
- Git commits are the single source of truth for implementation details
- Git tags for deployment versioning (e.g., v1.0.0-PROJ-1)

**Why:**
- Prevents context bloat (no growing FEATURE_CHANGELOG.md)
- Scales better (Git is built for large projects)
- No manual changelog maintenance
- Better developer experience (native Git workflow)

**Migration:**
- Requirements Engineer: Uses `ls features/` and `git ls-files` instead of FEATURE_CHANGELOG
- Solution Architect: Uses `git ls-files src/components/` to check existing code
- Frontend/Backend Devs: Use `git log --grep="PROJ-X"` to see feature history
- QA Engineer: Adds test results directly to feature spec
- DevOps: Updates feature spec with deployment status + creates Git tags

**Files changed:**
- Updated all 6 agent instructions (.claude/agents/*.md)
- Deleted FEATURE_CHANGELOG.md
- Deleted test-reports/ folder
- Updated PROJECT_CONTEXT.md (removed references)
- Updated README.md (v1.4.0, updated workflow)
- Updated features/README.md (new format with QA + Deployment sections)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

features/README.md

@@ -45,21 +45,68 @@ ProjectDashboard
 │   └── ProjectCard
 ```
 
+### 5. QA Test Results (vom QA Engineer)
+Am Ende des Feature-Dokuments fügt QA die Test-Ergebnisse hinzu:
+```markdown
+---
+
+## QA Test Results
+
+**Tested:** 2026-01-12
+**App URL:** http://localhost:3000
+
+### Acceptance Criteria Status
+- [x] AC-1: User kann Email + Passwort eingeben
+- [x] AC-2: Passwort mindestens 8 Zeichen
+- [ ] ❌ BUG: Doppelte Email wird nicht abgelehnt
+
+### Bugs Found
+**BUG-1: Doppelte Email-Registrierung**
+- **Severity:** High
+- **Steps to Reproduce:** 1. Register with email, 2. Try again with same email
+- **Expected:** Error message
+- **Actual:** Silent failure
+```
+
+### 6. Deployment Status (vom DevOps Engineer)
+```markdown
+---
+
+## Deployment
+
+**Status:** ✅ Deployed
+**Deployed:** 2026-01-13
+**Production URL:** https://your-app.vercel.app
+**Git Tag:** v1.0.0-PROJ-1
+```
+
 ## Workflow
 
 1. **Requirements Engineer** erstellt Feature Spec
 2. **User** reviewed Spec und gibt Feedback
 3. **Solution Architect** fügt Tech-Design hinzu
 4. **User** approved finales Design
-5. **Frontend/Backend Devs** implementieren
-6. **QA Engineer** testet gegen Acceptance Criteria
-7. **DevOps** deployed
+5. **Frontend/Backend Devs** implementieren (dokumentiert via Git Commits)
+6. **QA Engineer** testet und fügt Test-Ergebnisse zum Feature-Dokument hinzu
+7. **DevOps** deployed und fügt Deployment-Status zum Feature-Dokument hinzu
 
 ## Status-Tracking
 
-Feature-Status wird in `PROJECT_CONTEXT.md` getrackt:
-- ⚪ Backlog
-- 🔵 Planned (Requirements geschrieben)
-- 🟡 In Review (User reviewt)
-- 🟢 In Development (Wird gebaut)
-- ✅ Done (Live + getestet)
+Feature-Status wird direkt im Feature-Dokument getrackt:
+```markdown
+# PROJ-1: Feature Name
+
+**Status:** 🔵 Planned | 🟡 In Progress | ✅ Deployed
+**Created:** 2026-01-12
+**Last Updated:** 2026-01-12
+```
+
+**Status-Bedeutung:**
+- 🔵 Planned – Requirements sind geschrieben, ready for development
+- 🟡 In Progress – Wird gerade gebaut
+- ✅ Deployed – Live in Production
+
+**Git als Single Source of Truth:**
+- Alle Implementierungs-Details sind in Git Commits
+- `git log --grep="PROJ-1"` zeigt alle Änderungen für dieses Feature
+- Keine separate FEATURE_CHANGELOG.md nötig!