Add V4V sidebar section with dashboard, settings, and history

- New V4V store with budget tracking, cap enforcement, and history
- Dashboard: live streaming status, per-episode + weekly budget bars, stats
- Settings: auto-enable toggle (guarded by caps), per-episode cap, weekly
  budget, default rate, info icons
- History: expandable list of past V4V episodes with recipient breakdowns
- Budget enforcement: streaming stops with toast when cap is hit
- Auto-streaming: starts automatically for V4V episodes when enabled
- Cap reached state: dashboard shows red card, ticker shows "(capped)"
- V4VIndicator: slimmed popup, AUTO badge, "open v4v" nav link
- Fix duplicate history entries on cap stop

src/components/sidebar/Sidebar.tsx

@@ -18,6 +18,7 @@ const NAV_ITEMS = [
   { id: "notifications" as const, label: "notifications", icon: "🔔" },
   { id: "follows" as const, label: "follows", icon: "♺" },
   { id: "zaps" as const, label: "zaps", icon: "⚡" },
+  { id: "v4v" as const, label: "v4v", icon: "⚡" },
   { id: "relays" as const, label: "relays", icon: "⟐" },
   { id: "settings" as const, label: "settings", icon: "⚙" },
   { id: "about" as const, label: "support", icon: "♥" },