chore(auth): remove legacy rc_auth_uid/rc_uid/upsert_admin_user path; scope sign-in to ADMIN_ALLOWED_EMAILS; silence lockfile warning

Cleanup after Auth.js v5 became the only sign-in path. The platform
had three overlapping auth modes (dev cookie, legacy rc_auth_uid, Auth.js
JWT) and a pile of dead-code pages/routes that only existed to support
the legacy path.

What changed:

* getAdminUser() now has only two auth paths:
    1. dev_session cookie (auto-issued by src/proxy.ts for /admin/* when
       ALLOW_DEV_LOGIN is enabled)
    2. Auth.js v5 JWT (the encrypted cookie + auth() lookup)
  The legacy rc_auth_uid/rc_uid branch and the Supabase REST fetch
  against admin_users are gone.

* The signIn callback in src/lib/auth.ts enforces ADMIN_ALLOWED_EMAILS
  when set. Unset = open mode (backward compatible with demo/dev). Dev
  credentials provider is exempt. The new env var is wired through
  .env.example and .gitea/workflows/deploy.yml (read from
  secrets.ADMIN_ALLOWED_EMAILS, written to the server .env file).

* change-password/page.tsx now uses auth() server-side instead of
  fetching the deleted /api/auth/uid endpoint. The form is split into
  page.tsx (server component, auth check) + ChangePasswordForm.tsx
  (client component, form state). updatePasswordAction now reads the
  user id from auth() instead of the rc_auth_uid cookie.

* Deleted 14 dead-code files:
    - Pages: login2, logout, auth/callback, admin/debug-auth,
      admin/test-auth
    - API routes: api/login, api/logout, api/auth/uid, api/force-admin,
      api/set-auth-cookie, api/debug-cookie, api/debug-me,
      api/debug-auth
    - Actions: src/actions/login.ts
  These were the old email/password login, the old Supabase OAuth
  callback, the old /api/auth/uid probe, and a pile of debug endpoints
  that have been superseded by the new proxy + the new /login page.

* next.config.ts: set outputFileTracingRoot: '.' to silence the
  Next.js 16 lockfile-inference warning. Without this the build
  walked up from package.json looking for a lockfile, found the
  homelab runner's stale act cache at /home/tyler/.cache/act/.../package-lock.json,
  and warned on every build. '. resolves to the project root in both
  dev and CI, so it's the right answer.

Out of scope (deferred):

* src/actions/admin/users.ts still uses rc_auth_uid internally for its
  dev-bypass logic. It works (the rc_auth_uid branch is gated on
  NODE_ENV != 'production' and DEV_FORCE_UID), but it's now genuinely
  unreachable in production. Clean up in a follow-up.

Pre-flight:
* npx tsc --noEmit: clean
* npm run lint (touched files): clean
* npm run build: clean — proxy picked up, no lockfile warning, all
  93 static pages generated.

src/app/admin/debug-auth/page.tsx

@@ -1,60 +0,0 @@
-import { cookies } from "next/headers";
-
-export default async function DebugAuthPage() {
-  const cookieStore = await cookies();
-  const allCookies = cookieStore.getAll();
-  const rcAuthUid = cookieStore.get("rc_auth_uid")?.value;
-  const rcUid = cookieStore.get("rc_uid")?.value;
-  const rcAccessToken = cookieStore.get("rc_access_token")?.value;
-
-  let adminUsersStatus = "not_tried";
-  let adminUsersResult: string | null = null;
-
-  if (rcAuthUid) {
-    const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL;
-    const serviceKey = process.env.SUPABASE_SERVICE_ROLE_KEY;
-    if (supabaseUrl && serviceKey) {
-      try {
-        const res = await fetch(
-          `${supabaseUrl}/rest/v1/admin_users?user_id=eq.${rcAuthUid}&limit=1`,
-          { headers: { apikey: serviceKey, "Content-Type": "application/json" } }
-        );
-        adminUsersStatus = String(res.status);
-        const data = await res.json().catch(() => null);
-        adminUsersResult = JSON.stringify(data);
-      } catch (e) {
-        adminUsersStatus = "error: " + (e instanceof Error ? e.message : String(e));
-      }
-    } else {
-      adminUsersStatus = "missing_env_vars";
-    }
-  } else {
-    adminUsersStatus = "no_rc_auth_uid_cookie";
-  }
-
-  return (
-    <div className="min-h-screen bg-zinc-950 p-8 text-white">
-      <h1 className="text-2xl font-bold text-emerald-400 mb-6">Auth Debug</h1>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">Cookies ({allCookies.length})</h2>
-        <pre className="bg-black/50 p-4 rounded-xl text-xs overflow-auto max-h-64">
-          {allCookies.map(c => `${c.name}=${c.value.slice(0, 80)}${c.value.length > 80 ? "..." : ""}`).join("\n") || "(none)"}
-        </pre>
-      </div>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">Key Cookies</h2>
-        <p>rc_auth_uid: <span className={rcAuthUid ? "text-emerald-400" : "text-red-400"}>{rcAuthUid ? `${rcAuthUid.slice(0, 20)}...` : "NOT SET"}</span></p>
-        <p>rc_uid: <span className={rcUid ? "text-emerald-400" : "text-red-400"}>{rcUid ? `${rcUid.slice(0, 20)}...` : "NOT SET"}</span></p>
-        <p>rc_access_token: <span className={rcAccessToken ? "text-yellow-400" : "text-red-400"}>{rcAccessToken ? "PRESENT" : "NOT SET"}</span></p>
-      </div>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">Admin Users Lookup</h2>
-        <p>Status: <span className="text-lg font-mono">{adminUsersStatus}</span></p>
-        <p>Result: <pre className="bg-black/50 p-4 rounded-xl text-xs overflow-auto mt-2">{adminUsersResult || "(none)"}</pre></p>
-      </div>
-    </div>
-  );
-}

src/app/admin/test-auth/page.tsx

@@ -1,90 +0,0 @@
-import { getAdminUser } from "@/lib/admin-permissions";
-import { cookies } from "next/headers";
-
-export const dynamic = "force-dynamic";
-
-export default async function TestAuthPage() {
-  const cookieStore = await cookies();
-  const allCookies = cookieStore.getAll();
-
-  let adminUser = null;
-  let error: string | null = null;
-
-  try {
-    adminUser = await getAdminUser();
-  } catch (e: unknown) {
-    error = e instanceof Error ? e.message : String(e);
-  }
-
-  return (
-    <div className="min-h-screen bg-zinc-950 p-8 text-white">
-      <h1 className="text-2xl font-bold mb-6 text-emerald-400">Auth Debug</h1>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">All Cookies ({allCookies.length})</h2>
-        <pre className="bg-black/50 p-4 rounded-xl text-xs overflow-auto max-h-64">
-          {allCookies.map(c => `${c.name}=${c.value.slice(0, 80)}${c.value.length > 80 ? "..." : ""}`).join("\n") || "(none)"}
-        </pre>
-      </div>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">rc_auth_uid</h2>
-        <p className="text-lg font-mono">
-          {allCookies.some(c => c.name === "rc_auth_uid")
-            ? <span className="text-emerald-400">SET — {allCookies.find(c => c.name === "rc_auth_uid")?.value}</span>
-            : <span className="text-red-400">NOT SET</span>
-          }
-        </p>
-      </div>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">rc_access_token</h2>
-        <p className="text-lg font-mono">
-          {allCookies.some(c => c.name === "rc_access_token")
-            ? <span className="text-yellow-400">SET (not needed)</span>
-            : <span className="text-zinc-500">NOT SET (OK)</span>
-          }
-        </p>
-      </div>
-
-      <div className="mb-6">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">getAdminUser() result</h2>
-        {error ? (
-          <div>
-            <p className="text-red-400 font-bold">ERROR</p>
-            <pre className="bg-red-950/50 p-4 rounded-xl text-sm mt-2">{error}</pre>
-          </div>
-        ) : adminUser ? (
-          <div>
-            <p className="text-emerald-400 font-bold">AUTHENTICATED</p>
-            <pre className="bg-black/50 p-4 rounded-xl text-sm mt-2 overflow-auto">
-              {JSON.stringify({
-                id: adminUser.id,
-                user_id: adminUser.user_id,
-                role: adminUser.role,
-                brand_id: adminUser.brand_id,
-                active: adminUser.active,
-              }, null, 2)}
-            </pre>
-          </div>
-        ) : (
-          <p className="text-red-400">NOT AUTHENTICATED — null returned</p>
-        )}
-      </div>
-
-      <div className="mt-8 pt-4 border-t border-zinc-800">
-        <h2 className="text-xs font-semibold text-stone-400 uppercase mb-2">Quick Actions</h2>
-        <div className="flex gap-4">
-          <a href="/admin" className="px-4 py-2 bg-emerald-600 text-white rounded-xl text-sm font-bold hover:bg-emerald-500">
-            Go to Admin
-          </a>
-          <form action="/api/logout" method="POST">
-            <button type="submit" className="px-4 py-2 bg-zinc-800 text-white rounded-xl text-sm font-bold hover:bg-zinc-700">
-              Logout
-            </button>
-          </form>
-        </div>
-      </div>
-    </div>
-  );
-}