Portal sign-in with the Ecare office login

Ecare staff sign in with their office username and password, checked by
the Ecare sign-in service from the backend (AUTH_TOKEN_API_URL); a good
Ecare login still needs a Portal User. Service down = "try again
shortly", never a wrong password. /api/auth/login, me, logout; sign-in
tries limited per address. Users page: Ecare office login or Portal
password per user. Context.md: 27/10 runs, the login retry bug.
71 test files, 1239 tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.env.example

@@ -307,3 +307,7 @@ CAPTCHA_ATTEMPTS=2
 #   RESULTS_DB_CONN=DRIVER={ODBC Driver 18 for SQL Server};SERVER=<host>;DATABASE=Charge_Validation;UID=<sql login>;PWD=<password>;TrustServerCertificate=yes;
 #   PORTAL_URLS=https://<the address people type>
 #   PORTAL_SERVER=1
+# Ecare staff sign in with their Ecare office login (asked from the server,
+# never the browser); a user still has to be added on the Users page. Empty:
+# Portal passwords only.
+#   AUTH_TOKEN_API_URL=https://auth-wfm.ecareindia.com/api/login/token