Edit message #31

Allow users to edit a sent message within a short time window (e.g., 15 minutes).

Backend

• PUT /api/messages/:id – update the content and set an edited_at timestamp
• Enforce time limit and sender ownership

Frontend

• Long‑press → “Edit” option (only if within time limit)
• Show an inline editing view with the current text
• After saving, display “(edited)” next to the message timestamp
• Update the message in real time for the recipient via WebSocket

Keep it simple; no history of edits needed for now.