Add Quote / Repost (NIP-18, roadmap #6)

- publishRepost: kind 6 event with stringified original event as content
  and ["e", id, "", "mention"] + ["p", pubkey] tags
- publishQuote: kind 1 note with user's text + appended nostr:nevent1...
  reference and ["q", id] + ["p", pubkey] tags
- QuoteModal: compose modal with live quoted-note preview (avatar, name,
  truncated content); Ctrl+Enter to post, Escape to close
- NoteCard: "repost" (one-click, shows "reposted ✓") and "quote" (opens
  QuoteModal) added to the actions row alongside reply/like/zap

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/feed/NoteCard.tsx

@@ -6,9 +6,10 @@ import { useUserStore } from "../../stores/user";
 import { useMuteStore } from "../../stores/mute";
 import { useUIStore } from "../../stores/ui";
 import { timeAgo, shortenPubkey } from "../../lib/utils";
-import { publishReaction, publishReply, getNDK } from "../../lib/nostr";
+import { publishReaction, publishReply, publishRepost, getNDK } from "../../lib/nostr";
 import { NoteContent } from "./NoteContent";
 import { ZapModal } from "../zap/ZapModal";
+import { QuoteModal } from "./QuoteModal";
 
 interface NoteCardProps {
   event: NDKEvent;
@@ -40,6 +41,9 @@ export function NoteCard({ event }: NoteCardProps) {
   const [replySent, setReplySent] = useState(false);
   const replyRef = useRef<HTMLTextAreaElement>(null);
   const [showZap, setShowZap] = useState(false);
+  const [showQuote, setShowQuote] = useState(false);
+  const [reposting, setReposting] = useState(false);
+  const [reposted, setReposted] = useState(false);
   const [menuOpen, setMenuOpen] = useState(false);
 
   const handleLike = async () => {
@@ -83,6 +87,17 @@ export function NoteCard({ event }: NoteCardProps) {
     if (e.key === "Escape") setShowReply(false);
   };
 
+  const handleRepost = async () => {
+    if (reposting || reposted) return;
+    setReposting(true);
+    try {
+      await publishRepost(event);
+      setReposted(true);
+    } finally {
+      setReposting(false);
+    }
+  };
+
   return (
     <article className="border-b border-border px-4 py-3 hover:bg-bg-hover transition-colors duration-100 group/card">
       <div className="flex gap-3">
@@ -169,6 +184,21 @@ export function NoteCard({ event }: NoteCardProps) {
               >
                 {liked ? "♥" : "♡"}{reactionCount !== null && reactionCount > 0 ? ` ${reactionCount}` : liked ? " liked" : " like"}
               </button>
+              <button
+                onClick={handleRepost}
+                disabled={reposting || reposted}
+                className={`text-[11px] transition-colors disabled:cursor-default ${
+                  reposted ? "text-accent" : "text-text-dim hover:text-accent"
+                }`}
+              >
+                {reposted ? "reposted ✓" : reposting ? "…" : "repost"}
+              </button>
+              <button
+                onClick={() => setShowQuote(true)}
+                className="text-[11px] text-text-dim hover:text-text transition-colors"
+              >
+                quote
+              </button>
               <button
                 onClick={() => setShowZap(true)}
                 className="text-[11px] text-text-dim hover:text-zap transition-colors"
@@ -186,6 +216,15 @@ export function NoteCard({ event }: NoteCardProps) {
             />
           )}
 
+          {showQuote && (
+            <QuoteModal
+              event={event}
+              authorName={name}
+              authorAvatar={avatar}
+              onClose={() => setShowQuote(false)}
+            />
+          )}
+
           {/* Inline reply box */}
           {showReply && (
             <div className="mt-2 border-l-2 border-border pl-3">