Replace Andmore ID SSO with local login

fitme3070.pt delegated all authentication to hub.andmore.pt: views/auth/*
were bounce stubs, and because this domain is outside the .andmore.pt cookie
scope the real handoff was a one-time HTTPS ticket redeem. Bring identity back
in-house — passwords live in users.password_hash, which the SSO migration
never dropped.

Removed: config/sso.php, IDENTITY_MODE, every SSO_* constant and env key,
identity_is_federated() and the cookie/ticket paths in the auth views and the
public-site bootstrap. ANDMORE_ID_URL stays — it is still the hub /notify
endpoint for outbound email/SMS, which the reset mails ride on, and has
nothing to do with authentication now.

Added, ported from the fotografia.andmore.pt sibling rather than invented:

  - auth_login() with transparent password_needs_rehash upgrades and the
    last_login trail; auth_register_client(); auth_set_password(); the
    single-use 2h reset tokens.
  - Real login / register / forgot_password / reset_password pages on a new
    anonymous shell (includes/auth_header.php). includes/header.php renders
    the backoffice sidebar and a logout button, which is wrong for a visitor
    who is not signed in yet.
  - safe_return_path(), so a crafted ?return_to= cannot bounce a freshly
    authenticated user off-site.
  - Per-IP throttling on login, register and reset-request. Successes count
    too, so a guessed password cannot be parlayed into stuffing the rest of
    the user list from the same IP.
  - views/user/set_password.php: admin override for anyone whose email is
    undeliverable. Prefers mailing an invite link so the backoffice never
    handles the password. A plain admin cannot act on a sysadmin, and nobody
    can use it on themselves — self-service goes through profile.php, which
    demands the current password so a hijacked session cannot lock the owner
    out.

Accounts provisioned during the SSO era have password_hash NULL. They get in
via the reset email, or by registering again with the same address:
auth_register_client() claims a passwordless row, but only a plain `client`
one, so knowing a staff address does not let anyone self-assign the role.

users.andmore_id is deliberately left in place. No code reads it any more, but
it records which central identity each row was linked to.

Deployment: apply database/migration_20260913_local_auth.sql (password_resets
+ auth_attempts) in the SAME sysadmin session that pulls this commit — the
forgot-password flow needs that table, and after the pull a login requires a
local password.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

config/functions.php

@@ -2,19 +2,19 @@
 // ─── Bootstrap chain ─────────────────────────────────────────────────────────
 // Loaded by every page right after config/db.php (which opens $pdo and starts
 // the FIT_SESS session). Mirrors the fotografia/Andmore fleet shape, trimmed to
-// what fitme3070 needs this pass: settings, generic CRUD, auth + SSO, the
+// what fitme3070 needs this pass: settings, generic CRUD, local auth, the
 // migrations runner, and the centralized notify façade. Domain CRUD
 // (plataforma_fitness, team, modalidades, horário, galerias) is added per
 // feature in a follow-up under config/functions_*.php.
 
 if (session_status() === PHP_SESSION_NONE) session_start();
 
-require_once __DIR__ . '/config.php';              // APP_ENV + identity/SSO consts + error_handler
+require_once __DIR__ . '/config.php';              // APP_ENV + hub notify URL + error_handler
 require_once __DIR__ . '/functions_settings.php';  // setting() + system_settings cache
 require_once __DIR__ . '/functions_db.php';        // generic DB helpers
-require_once __DIR__ . '/functions_user.php';      // backoffice user creators (setup + admin/staff)
+require_once __DIR__ . '/functions_user.php';      // auth_login/register, password reset, user creators
 require_once __DIR__ . '/auth.php';                // require_login/admin/staff/sysadmin(), role helpers
-require_once __DIR__ . '/sso.php';                 // sso_resolve_session() + upstream link/cookie
+require_once __DIR__ . '/functions_throttle.php';  // per-IP attempt throttle for the auth endpoints
 require_once __DIR__ . '/functions_migrations.php';// platform_update.php migrations runner
 
 // Outbound delivery is centralized at id.andmore.pt — no local PHPMailer/SMTP.