feat(app): UI parity with Pencil mockup — top bar, panel cards, sidebar/event-center polish

Top bar (breadcrumb + actions + account), rounded panel cards with active
accent + rich headers, sidebar count pills/collapsible groups/daemon footer,
preset chips + scrollback pill, Event Center tabs + external-notify footer,
JetBrains Mono + Inter via @fontsource, shared theme tokens. Backend-absent
pieces are mocked (search, zoom, uptime, channels) pending SP1–SP5.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/package.json

@@ -9,10 +9,13 @@
     "tauri": "tauri"
   },
   "dependencies": {
+    "@fontsource-variable/jetbrains-mono": "^5.2.8",
+    "@fontsource/inter": "^5.2.8",
     "@tauri-apps/api": "^2",
     "@tauri-apps/plugin-notification": "^2",
-    "@xterm/xterm": "^5.5.0",
     "@xterm/addon-webgl": "^0.18.0",
+    "@xterm/xterm": "^5.5.0",
+    "lucide-react": "^1.17.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1"
   },