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/_comment_form.html

@@ -7,10 +7,10 @@
     </a>
     <textarea name="content" placeholder="Your opinion goes here..." required maxlength="1000" class="emoji-picker-target" data-mention></textarea>
     <div class="comment-form-actions">
-        <div class="attachment-upload-container" data-attachment-upload
-             data-max-size="{{ max_upload_size_mb() }}"
-             data-max-files="{{ max_attachments_per_resource() }}"
-             data-allowed-types="{{ allowed_file_types() }}"></div>
+        <dp-upload multiple
+            max-size="{{ max_upload_size_mb() }}"
+            max-files="{{ max_attachments_per_resource() }}"
+            allowed-types="{{ allowed_file_types() }}"></dp-upload>
         <button type="submit" class="comment-form-submit"><span class="icon">&#x1F4E4;</span> Post</button>
     </div>
 </form>