## Implementation Plan: Add Devlog Timeline of Related Posts to Project Page

### Changes Required

1. **`database/schema.py`**
   - Add index on `posts.project_uid` in `init_db()` after the table creation block:
     ```python
     cursor.execute("CREATE INDEX IF NOT EXISTS idx_posts_project_uid ON posts(project_uid)")
     ```
   - No backfill needed — `project_uid` column already exists with `NULL` default for old posts.

2. **`schemas/listings.py`**
   - In `ProjectDetailOut`, add a field:
     ```python
     project_posts: list[PostSummaryOut] = []
     ```
   - Import `PostSummaryOut` from `schemas/content.py`.

3. **`routers/projects/index.py`**
   - In `project_detail()` function, after fetching the project and existing fields, add a query for posts attached to this project:
     ```python
     from routers.posts import enrich_items
     rows = cursor.execute(
         "SELECT * FROM posts WHERE project_uid = ? AND deleted_at IS NULL ORDER BY created_at DESC LIMIT 50",
         (project.uid,)
     ).fetchall()
     posts = [PostInDB(**row) for row in rows]
     enriched = enrich_items(cursor, posts)
     project_dict["project_posts"] = enriched  # already serialized
     ```
   - Ensure `ProjectInDB` is imported (likely already present).

4. **`templates/project_detail.html`**
   - Add a tab button in the tab bar (inside `<div class="tabs">`):
     ```html
     <button class="tab" data-tab="devlog">Devlog</button>
     ```
   - Add the tab content section after the other tab contents:
     ```html
     <div class="tab-content" id="devlog">
       <h2>Devlog</h2>
       {% if project_posts %}
         <ul class="post-list">
           {% for post in project_posts %}
             <li>
               <a href="/posts/{{ post.slug }}">{{ post.title }}</a>
               <span class="date">{{ post.created_at }}</span>
             </li>
           {% endfor %}
         </ul>
       {% else %}
         <p>No posts yet for this project.</p>
       {% endif %}
     </div>
     ```
   - Make sure the template receives `project_posts` (already added in router step).

5. **`static/css/projects.css`**
   - Add styling for the devlog tab and post list:
     ```css
     .tab-content#devlog .post-list {
       list-style: none;
       padding: 0;
     }
     .tab-content#devlog .post-list li {
       padding: 0.5rem 0;
       border-bottom: 1px solid #eee;
     }
     .tab-content#devlog .post-list li:last-child {
       border-bottom: none;
     }
     ```

6. **`tests/api/projects/index.py`** (create if not exists)
   - Add test:
     ```python
     def test_project_detail_returns_related_posts(client, db):
         # Create project
         proj = create_project()
         # Create post attached to project
         post = create_post(project_uid=proj.uid)
         response = client.get(f"/projects/{proj.slug}")
         assert response.status_code == 200
         data = response.json()
         assert "project_posts" in data
         assert len(data["project_posts"]) == 1
         assert data["project_posts"][0]["uid"] == post.uid
     ```
   - Use existing helpers like `create_project`, `create_post` from conftest.

---

### Definition of Done

- [ ] All code changes described above are applied and committed.
- [ ] New index on `posts.project_uid` exists in database schema.
- [ ] `ProjectDetailOut` schema includes `project_posts` field as a list of `PostSummaryOut`.
- [ ] Project detail API endpoint returns `project_posts` array when posts are attached.
- [ ] Project page HTML shows a "Devlog" tab with the post list (or "No posts yet" message).
- [ ] Tab styling is consistent with existing tabs.
- [ ] The following test command passes:
  ```
  pip install -e '.[dev]' -q && python -m pytest tests/api/projects/index.py
  ```
- [ ] Manual verification: on a project with attached posts, the Devlog tab appears and displays posts in reverse chronological order; other tabs (About, Followers) remain functional.
- [ ] No regression in unrelated tests (dialog/gist failures are pre-existing and not caused by these changes).