Initial commit: StackPilot Phase 1 (Core)

Self-hosted Docker Compose manager.
- Backend: FastAPI + docker-py + SQLite (JWT auth, file-first stacks,
  lifecycle, live status, WebSocket logs, docker-run converter, audit log)
- Frontend: React + Vite + Tailwind (login/setup, dashboard, stacks,
  stack detail, Monaco editor, dark/light theme)
- Deployment: docker-compose.yml, Dockerfiles, nginx reverse proxy

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/pages/Placeholder.tsx

@@ -0,0 +1,20 @@
+import { Construction } from "lucide-react";
+import { Card } from "@/components/ui";
+
+export function Placeholder({ title, phase }: { title: string; phase: string }) {
+  return (
+    <Card className="flex flex-col items-center gap-3 py-16 text-center">
+      <Construction className="h-10 w-10 text-slate-400" />
+      <h2 className="text-lg font-semibold">{title}</h2>
+      <p className="max-w-md text-sm text-slate-500">
+        This section is part of {phase}. The backend foundation is ready — the UI
+        lands in an upcoming build phase.
+      </p>
+    </Card>
+  );
+}
+
+export const Networks = () => <Placeholder title="Networks" phase="Phase 2" />;
+export const Images = () => <Placeholder title="Images" phase="Phase 3" />;
+export const Templates = () => <Placeholder title="Templates" phase="Phase 3" />;
+export const Settings = () => <Placeholder title="Settings" phase="Phase 4" />;