feat: add DiceBear avatar proxy with style picker on signup and profile pages

Implement avatar generation via local proxy at `/avatar/{style}/{seed}` that fetches from DiceBear 9.x API with in-memory caching and fallback to initial-based SVG. Add avatar style selection dropdown to signup form and profile edit page, storing `avatar_style` in user records. Update comment rendering to support nested threading with parent-child relationships in post view. Add `avatar_url` and `avatar_styles` template globals, register avatar router in main app, and include avatar CSS classes for rounded image display.

README.md

@@ -0,0 +1,91 @@
+# DevPlace — The Developer Social Network
+
+Server-rendered social network for developers. FastAPI backend serving Jinja2 templates with ES6 interactivity. Avatar generation via DiceBear proxy. SQLite storage via `dataset`.
+
+## Quick start
+
+```bash
+make install        # pip install -e .
+make dev            # uvicorn --reload on port 10500
+make test           # 95 Playwright integration tests, headless
+make test-headed    # same tests in visible browser
+make demo           # absurd full-journey demo (headed)
+```
+
+Open `http://localhost:10500`.
+
+## Stack
+
+| Layer | Technology |
+|-------|-----------|
+| Backend | Python 3.13+, FastAPI, Uvicorn |
+| Templates | Jinja2 (server-side rendered) |
+| Frontend | Pure ES6 JavaScript, one class per file |
+| Database | SQLite via `dataset` (auto-sync schema, `uid` PKs) |
+| Auth | Session cookies, SHA256+SALT via passlib |
+| Avatars | DiceBear 9.x via local proxy (`/avatar/{style}/{seed}`) |
+| Validation | `hawk` (Python/JS/CSS/HTML) |
+
+## Project structure
+
+```
+devplacepy/
+  main.py             # FastAPI app, router registration
+  config.py           # Settings from env vars + .env
+  database.py         # dataset connection, index creation
+  templating.py       # Shared Jinja2 environment + globals
+  avatar.py           # DiceBear styles, URL generation
+  utils.py            # Password hashing, session mgmt, time_ago
+  models.py           # Pydantic schemas (validated but unused in routes)
+  routers/            # One file per domain (auth, feed, posts, ...)
+  templates/          # Jinja2 HTML templates
+  static/css/         # Page-specific CSS files
+  static/js/          # Application.js (ES6 module)
+```
+
+## Routes
+
+| Prefix | Purpose |
+|--------|---------|
+| `/auth` | Signup, login, logout |
+| `/feed` | Post feed with topic/tab filtering |
+| `/posts` | Post detail, creation |
+| `/comments` | Comment creation, deletion |
+| `/projects` | Project listing, creation |
+| `/profile` | Profile view, editing |
+| `/messages` | Direct messaging |
+| `/notifications` | Notification list, mark read |
+| `/votes` | Upvote/downvote on posts and comments |
+| `/avatar` | DiceBear avatar proxy with caching |
+
+## API
+
+No REST API — everything is form-based POST + redirect. All state lives in the session cookie. Endpoints return HTML or redirect.
+
+## Configuration
+
+| Env var | Default | Purpose |
+|---------|---------|---------|
+| `DEVPLACE_DATABASE_URL` | `sqlite:///devplace.db` | Database connection string |
+| `SECRET_KEY` | hardcoded fallback | Session signing key |
+
+## Testing
+
+- **95 integration tests** across 9 files using Playwright (NOT pytest-playwright plugin)
+- Server starts as subprocess on port 10501 with isolated temp database
+- Test users `alice_test` / `bob_test` seeded via HTTP at session start
+- Failure screenshots auto-save to `/tmp/devplace_test_screenshots/`
+- Headed mode: `PLAYWRIGHT_HEADLESS=0 make test`
+
+## Feature workflow
+
+1. Implement the feature (router + template + CSS + JS)
+2. `hawk .` — validate all source files
+3. `make test` — run all 95 tests headless
+4. If adding new functionality, write Playwright tests in `tests/test_*.py`
+5. For visual features, take a screenshot and verify with `falcon describe`
+6. Update `AGENTS.md` if any new conventions were introduced
+
+## License
+
+MIT — DevPlace