fix: BB admin login no longer bounces to distribute

Problem: /admin/* pages redirect unauthed users to /login or /account,
both of which then hit middleware redirecting to distribute.relevant
mediaproperties.com. Distribute is on a different domain, so its session
cookie doesn't carry to broadcastbeat.com — sign-in there left admins
stranded on distribute's dashboard.

Fix:
  - Remove /login (and /register) from middleware REDIRECT_PATHS. wp-login,
    wp-admin, client-login still bounce to distribute.
  - /login is now a real BB sign-in form (was a redirect to /client-login).
  - Admin pages preserve return path via /login?next=<encoded path>.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/middleware.ts

@@ -1,15 +1,16 @@
 import { NextResponse, type NextRequest } from "next/server";
 
 // PR firms / writers authenticate at the distribute platform, not here.
+// Legacy WordPress URLs still bounce there. /login is now a real BB login
+// page so the admin backend can use its own session (the BB Supabase cookie
+// doesn't transfer from distribute's domain).
 const AUTH_TARGET = "https://distribution.relevantmediaproperties.com/login";
 
 const REDIRECT_PATHS = new Set<string>([
-  "/login",
   "/wp-login",
   "/wp-login.php",
   "/wp-admin",
   "/client-login",
-  "/register",
 ]);
 
 // ─── Server-side impression beacon (AdSanity-equivalent) ────────────────────
@@ -118,12 +119,10 @@ export async function middleware(req: NextRequest) {
 export const config = {
   matcher: [
     "/((?!api/|_next/|legacy/|.*\\.).*)",
-    "/login",
     "/wp-login",
     "/wp-login.php",
     "/wp-admin/:path*",
     "/wp-login/:path*",
     "/client-login",
-    "/register",
   ],
 };