Unify OpenCode and Codex starter kits

- Add .shared/prompts/ with tool-neutral prompts
- Add .opencode/config/project.md, rules/, skills/ from opencode-kit
- Add .codex/config/project.md from codex-kit
- Copy .shared/prompts/ to both .opencode/prompts/ and .codex/prompts/
- Add features/INDEX.md and features/README.md
- Update README with unified structure

The two original starter kits are now redundant.

.opencode/skills/docs/SKILL.md

@@ -0,0 +1,109 @@
+---
+name: docs
+description: Documents API endpoints, generates wiki structure, and tracks documentation coverage
+category: development
+---
+
+# Documentation Engineer
+
+Documents API endpoints, maintains wiki structure, and reports documentation gaps.
+
+## When to Use
+
+```
+/docs
+/docs api
+/docs wiki
+/docs check
+```
+
+## Sub-Commands
+
+### `/docs api`
+Scans `src/` for API endpoints and updates `docs/api/`.
+
+### `/docs wiki`
+Suggests or updates wiki structure in `docs/wiki/`.
+
+### `/docs check`
+Reports which endpoints/classes lack documentation.
+
+## Skill Steps
+
+### 1. Scan for API Endpoints
+- Search `src/` for route files (REST patterns: `*Route.php`, `*Controller.php`)
+- Search for HTTP method annotations: `@Route`, `@Get`, `@Post`, `@Put`, `@Delete`
+- Detect endpoint patterns in plain PHP files
+
+### 2. Update API Documentation
+- Create/update `docs/api/ENDPOINTS.md` with endpoint inventory
+- Create individual files per resource: `docs/api/users.md`, `docs/api/tasks.md`
+- Format:
+
+```markdown
+# Users API
+
+## Endpoints
+
+| Method | Path | Description |
+|--------|------|-------------|
+| GET | /api/users | List all users |
+| GET | /api/users/{id} | Get single user |
+| POST | /api/users | Create user |
+| PUT | /api/users/{id} | Update user |
+| DELETE | /api/users/{id} | Delete user |
+
+## Request/Response Examples
+
+### GET /api/users
+**Response:**
+```json
+{
+  "data": [...],
+  "total": 42,
+  "page": 1,
+  "per_page": 20
+}
+```
+```
+
+### 3. Wiki Structure
+If `docs/wiki/` doesn't exist, suggest structure:
+
+```
+docs/wiki/
+├── README.md           <- Wiki home
+├── getting-started.md  <- Setup guide
+├── api-reference.md    <- API overview
+├── database.md         <- DB schema
+└── deployment.md        <- Hosting guide
+```
+
+### 4. Documentation Coverage Report
+Track which classes/features have docs:
+
+| Class/File | Has Docs | Last Updated |
+|------------|----------|--------------|
+| UserController | ✅ docs/api/users.md | 2026-01-15 |
+| TaskController | ❌ missing | - |
+
+## Output
+
+- `docs/api/*.md` - API endpoint documentation
+- `docs/wiki/README.md` - Wiki home (if created)
+- Coverage report printed to user
+
+## Rules
+
+- Use English for all documentation content
+- One endpoint file per resource
+- Include request/response examples
+- Document error responses (400, 401, 403, 404, 500)
+- Keep docs in sync with code (check on every run)
+
+## Context Recovery
+
+If context is compacted:
+1. Re-scan `src/` for endpoint files
+2. Check which docs already exist
+3. Continue from missing documentation