Add zap history view (roadmap #9)

- fetchZapsReceived: kind 9735 filtered by #p tag (receipts)
- fetchZapsSent: kind 9734 filtered by authors (zap requests)
- ZapHistoryView: Received / Sent tabs with row count; header shows
  total sats in/out; each row: avatar, amount, counterpart name
  (clickable → profile), comment, time ago
- Receipt parsing: amount from embedded zap request in "description"
  tag (millisats → sats); sender from uppercase "P" tag with fallback
  to zap request pubkey
- Request parsing: amount from "amount" tag, recipient from "p" tag
- ⚡ zaps nav item added to sidebar between search and relays
- Logged-out fallback state with prompt to log in

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

src/stores/ui.ts

@@ -2,7 +2,7 @@ import { create } from "zustand";
 
 import { NDKEvent } from "@nostr-dev-kit/ndk";
 
-type View = "feed" | "search" | "relays" | "settings" | "profile" | "thread" | "article-editor" | "about";
+type View = "feed" | "search" | "relays" | "settings" | "profile" | "thread" | "article-editor" | "about" | "zaps";
 
 interface UIState {
   currentView: View;