Add 'Send private message' action to chat user sheet

[a1denvalu3]

Summary

Adds a "Send private message" option to the user action sheet, which appears when long-pressing a user's avatar or message in the chat. This allows users to quickly initiate a Direct Message (DM) without navigating back to the main peer list.

Changes

• UI: Added a "Send private message" row to ChatUserSheet. The action uses a distinct purple color to separate it from moderation actions (block/slap/hug).
• Logic:
  • Supports Mesh Chat: Resolves the peer ID and starts a private chat.
  • Supports Geohash Chat: Resolves the user's public key (via nickname or short ID) and initiates a Nostr-based DM.
• ViewModel: Added startGeohashDMByShortId and startGeohashDMByNickname to ChatViewModel and GeohashViewModel.
• Repository: Added findPubkeyByShortId to GeohashRepository to support looking up users by the 8-char short ID found in BitchatMessage.

Testing

• Verified on local build.
• Checked flow for both Bluetooth mesh peers and Geohash channel participants.

[chatgpt-codex-connector]

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[Michael679089]

Is the message sent directly to your favorite peer or is it still passed peer to peer?