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/u/[handle]/page.tsx

@@ -7,7 +7,7 @@ import { ArrowLeftIcon, CalendarIcon } from '@/components/Icons';
 import { PostCard } from '@/components/PostCard';
 import { User, Post } from '@/lib/types';
 import AutoTextarea from '@/components/AutoTextarea';
-import { Rocket, MoreHorizontal } from 'lucide-react';
+import { Rocket, MoreHorizontal, Mail } from 'lucide-react';
 import { formatFullHandle } from '@/lib/utils/handle';
 import { Bot } from 'lucide-react';
 
@@ -47,15 +47,15 @@ function UserRow({ user }: { user: UserSummary }) {
                 <div style={{ display: 'flex', alignItems: 'center', gap: '6px' }}>
                     <span style={{ fontWeight: 600 }}>{user.displayName || user.handle}</span>
                     {user.isBot && (
-                        <span 
-                            style={{ 
+                        <span
+                            style={{
                                 display: 'inline-flex',
                                 alignItems: 'center',
                                 gap: '3px',
-                                fontSize: '10px', 
-                                padding: '2px 6px', 
-                                borderRadius: '4px', 
-                                background: 'var(--accent-muted)', 
+                                fontSize: '10px',
+                                padding: '2px 6px',
+                                borderRadius: '4px',
+                                background: 'var(--accent-muted)',
                                 color: 'var(--accent)',
                                 fontWeight: 500,
                             }}
@@ -184,7 +184,7 @@ export default function ProfilePage() {
     // Infinite scroll observer
     useEffect(() => {
         if (!loadMoreRef.current) return;
-        
+
         const observer = new IntersectionObserver(
             (entries) => {
                 if (entries[0].isIntersecting) {
@@ -412,12 +412,12 @@ export default function ProfilePage() {
                 background: 'var(--background)',
                 zIndex: 10,
             }}>
-                <button 
-                    onClick={() => router.back()} 
-                    style={{ 
-                        color: 'var(--foreground)', 
-                        background: 'none', 
-                        border: 'none', 
+                <button
+                    onClick={() => router.back()}
+                    style={{
+                        color: 'var(--foreground)',
+                        background: 'none',
+                        border: 'none',
                         cursor: 'pointer',
                         padding: 0,
                         display: 'flex',
@@ -504,6 +504,12 @@ export default function ProfilePage() {
                                             {isFollowing ? 'Following' : 'Follow'}
                                         </button>
                                     )}
+                                    {/* Message Button (V2 Chat) */}
+                                    {user.did && (
+                                        <Link href={`/chat?compose=${user.handle}`} className="btn btn-ghost" style={{ padding: '8px' }}>
+                                            <Mail size={20} />
+                                        </Link>
+                                    )}
                                     <div style={{ position: 'relative' }}>
                                         <button
                                             className="btn btn-ghost"
@@ -623,7 +629,7 @@ export default function ProfilePage() {
                                     {(user as any).botOwner && (
                                         <>
                                             {' · Managed by '}
-                                            <Link 
+                                            <Link
                                                 href={`/u/${(user as any).botOwner.handle}`}
                                                 style={{ color: 'var(--accent)', fontWeight: 500 }}
                                             >
@@ -798,7 +804,7 @@ export default function ProfilePage() {
 
                 {/* Tabs */}
                 <div style={{ display: 'flex', borderTop: '1px solid var(--border)' }}>
-                    {(user?.isBot 
+                    {(user?.isBot
                         ? ['posts', 'replies', 'followers', 'following'] as const
                         : ['posts', 'replies', 'likes', 'followers', 'following'] as const
                     ).map(tab => (