Add attachment management CRUD to the /uploads API

Complete the read and update faces of the signed-in user's attachment
management over the existing attachments table:

- GET /uploads: paginated list of the user's own attachments, newest
  first, with an optional linked/orphaned filter
- GET /uploads/{uid}: fetch one attachment (owner or admin)
- PATCH /uploads/{uid}: rename the display filename, always preserving
  the original extension (owner or admin, audited as attachment.rename)

Adds get_user_attachments/get_user_attachment data helpers, the
rename_attachment operation, AttachmentRenameForm, the UploadItemOut and
UploadsListOut schemas, the Devii tools list_attachments/get_attachment/
rename_attachment, expanded API reference documentation for the full
lifecycle including delete, and api-tier tests.

README.md

@@ -69,7 +69,7 @@ devplacepy/
 | `/p/{slug}` | Public ingress proxy (HTTP + WebSocket) to a running container instance's published port, opt-in per instance via `ingress_slug` |
 | `/profile` | Profile view, editing, a public **Media** tab (`?tab=media`) showing every attachment a user uploaded newest first, and a live **online / last-seen** presence indicator |
 | `/media` | Per-attachment soft delete and restore: `POST /media/{uid}/delete` (owner or admin), `POST /media/{uid}/restore` (admin) |
-| `/uploads` | File upload endpoints: `POST /uploads/upload` (multipart), `POST /uploads/upload-url` (from URL); served at `/static/uploads/` |
+| `/uploads` | Attachment management (full lifecycle for the signed-in user, same files that appear on posts and other content): `POST /uploads/upload` (multipart) and `POST /uploads/upload-url` (from URL) create; `GET /uploads` lists your own attachments (paginated, newest first, optional `linked` filter); `GET /uploads/{uid}` returns one; `PATCH /uploads/{uid}` renames its display filename (the file extension is always preserved); `DELETE /uploads/delete/{uid}` removes one. Reading and modifying another user's attachment is owner-or-admin; files are served at `/static/uploads/` |
 | `/admin/trash` | Admin **Trash**: review, restore, and permanently purge soft-deleted content (posts, comments, gists, projects, news, project files, attachments) across the platform |
 | `/notifications` | Notification list, mark read, live unread counts (`/notifications/counts`) |
 | `/messages` | Real-time direct messaging over WebSocket (`/messages/ws`): live bidirectional delivery, optimistic send, typing indicators, read receipts, and online/last-seen presence. Messages render through the shared content pipeline (emoji shortcodes, image, video and audio embeds, autolink, sanitization). AI content correction and the AI modifier apply to direct messages, so typing an inline `@ai <instruction>` in a message executes it and the resolved result appears live in the chat for both participants (the `message` WS frame carries an additive `ai_processed` flag when a pending correction/modification was applied). An opened conversation loads its 500 most recent messages; older history is retained in the database. `GET /messages/conversations` returns the conversation list as JSON for a live client refresh; the `POST /messages/send` form remains as a no-JavaScript fallback and now accepts an attachment-only, empty-content message. `POST /messages/ws-ticket` exchanges a session/API-key auth to a short-lived (30s), single-use ticket a browser WebSocket can carry as `?ticket=...` on the handshake, since a native `WebSocket` cannot set an `Authorization`/`X-API-KEY` header - this is what makes off-session embedding of the chat possible. CLI: `devplace messaging prune-tickets` removes expired tickets |