feat: add project file system with CRUD, upload, inline editing, and video attachment support

- Add new `/projects/{slug}/files` endpoint group for per-project filesystem operations including directory and file CRUD, upload, and inline editing with public read and owner write access
- Extend attachment system to support video formats (webm, ogv, mov, m4v) with proper file icons and MIME types
- Implement configurable allowed file types via `allowed_file_types` site setting, replacing hardcoded `ALLOWED_UPLOAD_TYPES` with dynamic `allowed_extensions()` and `is_extension_allowed()` functions
- Add `delete_all_project_files()` call in `delete_content_item()` to clean up project files when a project is deleted
- Create database indexes on `project_files` table for `(project_uid, path)` and `(project_uid, parent_path)` to optimize file lookups
- Introduce `docs_prose.py` module with `render_prose()` function that renders Markdown content inside `data-render` divs using mistune, enabling dynamic prose rendering in documentation pages
- Enhance docs search with Markdown-aware text stripping (`_demarkdown()`) and improved HTML/script/style sanitization for better search indexing
- Update documentation API samples to reflect new attachment response fields (`is_image`, `is_video`, `mime_type`) and note video format support
- Update README to document the new project files endpoint and clarify AI gateway attribution for guest Devii sessions

devplacepy/templates/docs/component-emoji-picker.html

@@ -0,0 +1,51 @@
+<div class="docs-content" data-render>
+# emoji-picker
+
+A vendored third-party emoji picker (`emoji-picker-element`) with category browsing, search, and
+skin-tone selection. DevPlace loads it globally and uses it on comment forms via the
+`EmojiPicker` wrapper (textareas marked `.emoji-picker-target`).
+
+Source: `static/vendor/emoji-picker-element/`.
+
+## Attributes
+
+| Attribute | Description |
+|---|---|
+| `locale` | Language for emoji labels (for example `en`). |
+| `skin-tone-emoji` | Default skin-tone emoji. |
+| `emoji-version` | Restrict to a Unicode emoji version. |
+
+## Events
+
+| Event | Detail |
+|---|---|
+| `emoji-click` | `{ unicode, emoji, ... }` for the chosen emoji (primary event). |
+| `skin-tone-change` | The selected skin tone. |
+
+## Usage
+
+```html
+&lt;emoji-picker&gt;&lt;/emoji-picker&gt;
+```
+
+```javascript
+picker.addEventListener("emoji-click", (event) => {
+    insert(event.detail.unicode);
+});
+```
+</div>
+
+<div class="component-demo">
+    <div class="component-demo-title">Live example - pick an emoji</div>
+    <div class="component-demo-stage">
+        <emoji-picker></emoji-picker>
+        <span id="emoji-demo-result" class="text-muted">No emoji selected yet.</span>
+    </div>
+</div>
+<script type="module">
+    import "/static/vendor/emoji-picker-element/index.js";
+    const result = document.getElementById("emoji-demo-result");
+    document.querySelector(".component-demo emoji-picker").addEventListener("emoji-click", (event) => {
+        result.textContent = `Selected: ${event.detail.unicode}`;
+    });
+</script>