Unify console sign-in for connect authorize

Remove the separate portal login page, show OAuth client branding on
sign-in, and preserve authorize continue URLs across auth methods.

Signed-off-by: Bryan Frimin <bryan@probo.com>

apps/console/src/lib/buildAuthorizeContinueURL.ts

@@ -0,0 +1,45 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+const oauth2AuthorizePathSuffix = "/oauth2/authorize";
+
+function parseContinueUrl(continueParam: string | null): URL | null {
+  if (!continueParam) {
+    return null;
+  }
+
+  try {
+    return new URL(continueParam, window.location.origin);
+  } catch {
+    return null;
+  }
+}
+
+export function isOAuthAuthorizeContinueUrl(continueParam: string | null): boolean {
+  const url = parseContinueUrl(continueParam);
+  if (!url) {
+    return false;
+  }
+
+  return url.pathname.endsWith(oauth2AuthorizePathSuffix);
+}
+
+export function clientIdFromContinueUrl(continueParam: string | null): string | null {
+  const url = parseContinueUrl(continueParam);
+  if (!url) {
+    return null;
+  }
+
+  return url.searchParams.get("client_id");
+}