feat: add app shell with top bar, view routing, and board factory

src/App.tsx

@@ -1,7 +1,37 @@
+import { useEffect } from "react";
+import { useAppStore } from "@/stores/app-store";
+import { AppShell } from "@/components/layout/AppShell";
+
 export default function App() {
+  const initialized = useAppStore((s) => s.initialized);
+  const init = useAppStore((s) => s.init);
+  const view = useAppStore((s) => s.view);
+
+  useEffect(() => {
+    init();
+  }, [init]);
+
+  if (!initialized) {
+    return (
+      <div className="flex h-screen items-center justify-center bg-pylon-bg">
+        <span className="font-heading text-lg text-pylon-text-secondary">
+          Loading...
+        </span>
+      </div>
+    );
+  }
+
   return (
-    <div className="h-screen flex items-center justify-center bg-background text-foreground">
-      <h1 className="text-2xl font-bold">OpenPylon</h1>
-    </div>
+    <AppShell>
+      {view.type === "board-list" ? (
+        <div className="flex h-full items-center justify-center text-pylon-text-secondary">
+          Board List
+        </div>
+      ) : (
+        <div className="flex h-full items-center justify-center text-pylon-text-secondary">
+          Board View
+        </div>
+      )}
+    </AppShell>
   );
 }