Add profile view with clickable names/avatars

- ProfileView shows avatar, bio, nip05, website, recent notes
- Clicking any name or avatar navigates to their profile
- Add fetchUserNotes to nostr lib (kind 1 by author)
- Add openProfile action + selectedPubkey to UI store
- Back button returns to feed

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

src/stores/ui.ts

@@ -1,17 +1,21 @@
 import { create } from "zustand";
 
-type View = "feed" | "relays" | "settings";
+type View = "feed" | "relays" | "settings" | "profile";
 
 interface UIState {
   currentView: View;
   sidebarCollapsed: boolean;
+  selectedPubkey: string | null;
   setView: (view: View) => void;
+  openProfile: (pubkey: string) => void;
   toggleSidebar: () => void;
 }
 
 export const useUIStore = create<UIState>((set) => ({
   currentView: "feed",
   sidebarCollapsed: false,
+  selectedPubkey: null,
   setView: (currentView) => set({ currentView }),
+  openProfile: (pubkey) => set({ currentView: "profile", selectedPubkey: pubkey }),
   toggleSidebar: () => set((s) => ({ sidebarCollapsed: !s.sidebarCollapsed })),
 }));