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/api/client.ts

@@ -0,0 +1,50 @@
+import axios, { AxiosError } from "axios";
+import { useAuthStore } from "@/store/auth";
+
+const api = axios.create({ baseURL: "/" });
+
+api.interceptors.request.use((config) => {
+  const token = useAuthStore.getState().accessToken;
+  if (token) {
+    config.headers.Authorization = `Bearer ${token}`;
+  }
+  return config;
+});
+
+let refreshing: Promise<string | null> | null = null;
+
+api.interceptors.response.use(
+  (res) => res,
+  async (error: AxiosError) => {
+    const original = error.config as any;
+    if (error.response?.status === 401 && original && !original._retry) {
+      original._retry = true;
+      if (!refreshing) {
+        refreshing = useAuthStore
+          .getState()
+          .refresh()
+          .finally(() => {
+            refreshing = null;
+          });
+      }
+      const newToken = await refreshing;
+      if (newToken) {
+        original.headers.Authorization = `Bearer ${newToken}`;
+        return api(original);
+      }
+      useAuthStore.getState().logout();
+    }
+    return Promise.reject(error);
+  }
+);
+
+export function apiErrorMessage(err: unknown): string {
+  const e = err as AxiosError<any>;
+  const detail = e?.response?.data?.detail;
+  if (typeof detail === "string") return detail;
+  if (detail?.detail) return `${detail.error}: ${detail.detail}`;
+  if (detail?.error) return detail.error;
+  return e?.message || "Unexpected error";
+}
+
+export default api;