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/lib/utils.ts

@@ -0,0 +1,35 @@
+import { clsx, type ClassValue } from "clsx";
+import { twMerge } from "tailwind-merge";
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}
+
+export function formatBytes(bytes: number): string {
+  if (!bytes) return "0 B";
+  const units = ["B", "KB", "MB", "GB", "TB"];
+  const i = Math.floor(Math.log(bytes) / Math.log(1024));
+  return `${(bytes / Math.pow(1024, i)).toFixed(1)} ${units[i]}`;
+}
+
+export function formatUptime(seconds: number): string {
+  const d = Math.floor(seconds / 86400);
+  const h = Math.floor((seconds % 86400) / 3600);
+  const m = Math.floor((seconds % 3600) / 60);
+  if (d) return `${d}d ${h}h`;
+  if (h) return `${h}h ${m}m`;
+  return `${m}m`;
+}
+
+export function relativeTime(iso: string): string {
+  const then = new Date(iso).getTime();
+  const diff = Date.now() - then;
+  const s = Math.floor(diff / 1000);
+  if (s < 60) return "just now";
+  const m = Math.floor(s / 60);
+  if (m < 60) return `${m}m ago`;
+  const h = Math.floor(m / 60);
+  if (h < 24) return `${h}h ago`;
+  const d = Math.floor(h / 24);
+  return `${d}d ago`;
+}