Revamp chat UI and add V2 encrypted messaging support

Major update to chat page with new conversation list, message thread view, and support for V2 end-to-end encrypted messaging using DIDs. Adds chat lock state, message sending, conversation deletion, and improved polling. Updates user API and types to include DID and chatPublicKey. Fixes race conditions in feed loading, adds message button to user profile, and improves crypto and identity hooks for better locked/unlocked state detection.

src/app/api/users/[handle]/route.ts

@@ -97,6 +97,7 @@ export async function GET(request: Request, context: RouteContext) {
             isBot: user.isBot,
             publicKey: user.publicKey, // RSA key for signing
             chatPublicKey: user.chatPublicKey, // ECDH key for E2E chat
+            did: user.did, // V2 Identity
         };
 
         // If this is a bot, include owner info