Replace Alpine frontend with Next.js Claude Activity Dashboard (#7)

Rebuild the bundled web UI as a Next.js (React + TypeScript) static export
implementing the Claude Activity Dashboard design: a left-nav "Control Center"
hub over Runs, Repositories, Agents, Approvals, Git Servers, Activity, and
Shared, styled with the Leeworks design-system tokens (flat, dark, border-led).

The dashboard is a pure client of the existing API (same contract as curl):
the browser prompts for the token once, stores it in localStorage, attaches it
to every call, and renders all API values as React text so agent-authored
strings stay inert. Control actions enqueue a command and poll it to a terminal
state, matching the worker model.

The build output is committed to src/handler/api/static/ so the wheel ships it
and FastAPI serves it same-origin. app.py now mounts the export at "/" after the
API routers (a non-shadowing fallback: unmatched paths 404, no SPA rewrite).
UI-serving tests updated for the export; frontend source lives in frontend/.


Claude-Session: https://claude.ai/code/session_01ATgVWRjFzG8nHEnwgZpJWD

Co-authored-by: Claude <noreply@anthropic.com>

frontend/next.config.mjs

@@ -0,0 +1,12 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  // Static HTML/JS/CSS export. The Handler API (FastAPI) serves the built `out/`
+  // same-origin, exactly as it served the old Alpine shell — the browser calls the
+  // authed API with relative paths, so there is no separate frontend server to run.
+  output: "export",
+  reactStrictMode: true,
+  // The export is served from disk with no image optimizer behind it.
+  images: { unoptimized: true },
+};
+
+export default nextConfig;