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.

devplacepy/attachments.py

@@ -546,6 +546,21 @@ def delete_attachment(uid):
         _delete_attachment_row(row)
 
 
+def rename_attachment(uid, filename):
+    row = get_table("attachments").find_one(uid=uid, deleted_at=None)
+    if not row:
+        return None
+    ext = Path(row.get("stored_name", "")).suffix.lower()
+    stem = Path(str(filename)).name.strip()
+    if ext:
+        stem = Path(stem).stem
+    if not stem:
+        return None
+    clean = f"{stem}{ext}"
+    get_table("attachments").update({"uid": uid, "original_filename": clean}, ["uid"])
+    return clean
+
+
 def soft_delete_attachment(uid, deleted_by="system"):
     row = get_table("attachments").find_one(uid=uid)
     if not row or row.get("deleted_at"):