arcrun — AI workflow execution engine (clean history)

Self-hosted 開源：WASM 零件 + recipe + cypher-executor，跑在你自己的 Cloudflare。

此為重建的乾淨歷史起點（移除曾誤 commit 的 GCP SA 金鑰，舊歷史保留在
richblack/arcrun 與本地 backup 分支）。含：
- acr init --self-hosted installer（建 KV/R2 + codeload 拉預編譯 wasm + wrangler deploy + seed recipe）
- recipe push 把關（資料外流提醒 + 打通檢查）
- 19 個正當零件預編譯 wasm（claude_api/km_writer/kbdb_upsert_block 排除：違反 DECISIONS §1）
- CLI / cypher-executor / registry / 完整 SDD

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

landing/middleware.ts

@@ -0,0 +1,22 @@
+import { NextResponse } from 'next/server';
+import type { NextRequest } from 'next/server';
+
+export function middleware(request: NextRequest) {
+  const { pathname } = request.nextUrl;
+
+  // Protect /dashboard and /mira (login required; mira 額外白名單檢查在 layout)
+  if (pathname.startsWith('/dashboard') || pathname.startsWith('/mira')) {
+    const session = request.cookies.get('arcrun_session');
+    if (!session?.value) {
+      const loginUrl = new URL('/login', request.url);
+      loginUrl.searchParams.set('redirect', pathname);
+      return NextResponse.redirect(loginUrl);
+    }
+  }
+
+  return NextResponse.next();
+}
+
+export const config = {
+  matcher: ['/dashboard', '/dashboard/:path*', '/mira', '/mira/:path*'],
+};