Reply to messages

[mrsumanbiswas]

Add the ability to reply to a specific message in a conversation.

Backend

• The messages table should include an optional reply_to_message_id field
• When sending a reply, include the ID of the message being replied to
• The recipient should see which message is being quoted

Frontend

• Swipe or long‑press a message bubble to reveal a “Reply” action
• When replying, show the quoted message preview above the input field
• The sent message bubble should display the quoted text/attachment in a compact format
• Tapping the quoted part should scroll to the original message

Make sure this works in both one‑on‑one and group chats.