Add zaps: NWC wallet connect + NIP-57 zap flow

- NWC client (nwc.ts): parse URI, encrypt/send kind 23194, await kind 23195 response
- Lightning store: persist NWC URI to localStorage, zap() via NDKZapper + lnPay callback
- ZapModal: amount presets (21/100/500/1000/5000 sats), custom amount, optional comment,
  paying/success/error states, prompts to Settings if no wallet connected
- ⚡ zap button on NoteCard (action row) and ProfileView (header, next to follow)
- Settings > Lightning Wallet section: paste NWC URI, connect/disconnect

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

src/components/shared/SettingsView.tsx

@@ -1,5 +1,7 @@
 import { useState } from "react";
 import { useUserStore } from "../../stores/user";
+import { useLightningStore } from "../../stores/lightning";
+import { isValidNwcUri } from "../../lib/lightning/nwc";
 import { getNDK, getStoredRelayUrls, addRelay, removeRelay } from "../../lib/nostr";
 
 function RelayRow({ url, onRemove }: { url: string; onRemove: () => void }) {
@@ -121,6 +123,75 @@ function IdentitySection() {
   );
 }
 
+function WalletSection() {
+  const { nwcUri, setNwcUri, clearNwcUri } = useLightningStore();
+  const [input, setInput] = useState("");
+  const [error, setError] = useState<string | null>(null);
+  const [saving, setSaving] = useState(false);
+
+  const handleSave = () => {
+    const uri = input.trim();
+    if (!uri) return;
+    if (!isValidNwcUri(uri)) {
+      setError("Invalid NWC URI. Must start with nostr+walletconnect://");
+      return;
+    }
+    try {
+      setSaving(true);
+      setNwcUri(uri);
+      setInput("");
+      setError(null);
+    } catch (err) {
+      setError(String(err));
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  return (
+    <section>
+      <h2 className="text-text text-[11px] font-medium uppercase tracking-widest mb-2 text-text-dim">Lightning Wallet (NWC)</h2>
+      {nwcUri ? (
+        <div>
+          <div className="flex items-center gap-2 px-3 py-2 border border-border mb-2">
+            <span className="text-zap text-[11px]">⚡</span>
+            <span className="text-text text-[12px] flex-1">Wallet connected</span>
+            <button
+              onClick={clearNwcUri}
+              className="text-[10px] text-text-dim hover:text-danger transition-colors shrink-0"
+            >
+              disconnect
+            </button>
+          </div>
+          <p className="text-text-dim text-[10px] px-1">Your NWC connection is active. You can zap notes and profiles.</p>
+        </div>
+      ) : (
+        <div>
+          <textarea
+            value={input}
+            onChange={(e) => { setInput(e.target.value); setError(null); }}
+            placeholder="nostr+walletconnect://…"
+            rows={3}
+            className="w-full bg-bg border border-border px-3 py-2 text-text text-[11px] font-mono resize-none focus:outline-none focus:border-accent/50 placeholder:text-text-dim mb-2"
+            style={{ WebkitUserSelect: "text", userSelect: "text" } as React.CSSProperties}
+          />
+          {error && <p className="text-danger text-[11px] mb-2">{error}</p>}
+          <button
+            onClick={handleSave}
+            disabled={!input.trim() || saving}
+            className="px-4 py-1.5 text-[11px] border border-border text-text-muted hover:text-accent hover:border-accent/40 transition-colors disabled:opacity-30 disabled:cursor-not-allowed"
+          >
+            connect wallet
+          </button>
+          <p className="text-text-dim text-[10px] mt-2 px-1">
+            Get an NWC connection string from Alby, Mutiny, or any NWC-compatible wallet.
+          </p>
+        </div>
+      )}
+    </section>
+  );
+}
+
 export function SettingsView() {
   return (
     <div className="h-full flex flex-col">
@@ -129,6 +200,7 @@ export function SettingsView() {
       </header>
 
       <div className="flex-1 overflow-y-auto p-4 space-y-8">
+        <WalletSection />
         <RelaySection />
         <IdentitySection />
       </div>