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-lock.json

@@ -8,10 +8,13 @@
       "name": "spacesh-app",
       "version": "0.1.0",
       "dependencies": {
+        "@fontsource-variable/jetbrains-mono": "^5.2.8",
+        "@fontsource/inter": "^5.2.8",
         "@tauri-apps/api": "^2",
         "@tauri-apps/plugin-notification": "^2",
         "@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"
       },
@@ -697,6 +700,24 @@
         "node": ">=12"
       }
     },
+    "node_modules/@fontsource-variable/jetbrains-mono": {
+      "version": "5.2.8",
+      "resolved": "https://registry.npmjs.org/@fontsource-variable/jetbrains-mono/-/jetbrains-mono-5.2.8.tgz",
+      "integrity": "sha512-WBA9elru6Jdp5df2mES55wuOO0WIrn3kpXnI4+W2ek5u3ZgLS9XS4gmIlcQhiZOWEKl95meYdvK7xI+ETLCq/Q==",
+      "license": "OFL-1.1",
+      "funding": {
+        "url": "https://github.com/sponsors/ayuhito"
+      }
+    },
+    "node_modules/@fontsource/inter": {
+      "version": "5.2.8",
+      "resolved": "https://registry.npmjs.org/@fontsource/inter/-/inter-5.2.8.tgz",
+      "integrity": "sha512-P6r5WnJoKiNVV+zvW2xM13gNdFhAEpQ9dQJHt3naLvfg+LkF2ldgSLiF4T41lf1SQCM9QmkqPTn4TH568IRagg==",
+      "license": "OFL-1.1",
+      "funding": {
+        "url": "https://github.com/sponsors/ayuhito"
+      }
+    },
     "node_modules/@jridgewell/gen-mapping": {
       "version": "0.3.13",
       "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.13.tgz",
@@ -1691,6 +1712,15 @@
         "yallist": "^3.0.2"
       }
     },
+    "node_modules/lucide-react": {
+      "version": "1.17.0",
+      "resolved": "https://registry.npmjs.org/lucide-react/-/lucide-react-1.17.0.tgz",
+      "integrity": "sha512-9FA9evdox/JQL5PT57fdA1x/yg8T7knJ98+zjTL3UfKza6pflQUUh3XtaQIHKvnsJw1lmsEyHVlt5jchYxOQ5w==",
+      "license": "ISC",
+      "peerDependencies": {
+        "react": "^16.5.1 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/ms": {
       "version": "2.1.3",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",