feat(web): full auth screens rework to match design + old-app business rules

Rebuilt tenant/login/register/reset-password to match the design handoff's
01-account screens precisely (previously only loosely approximated), and
ported the old app's real business rules instead of guessing:

- LoginPage: desktop split branding panel (>=900px), terms-agreement
  checkbox gating submit, forgot-password link, password visibility toggle,
  full ctrl-error translation table (lib/tinode/errors.ts, ported from the
  old app's CTRL_ERROR_TEXT_CN/translateCtrlError -- registration/login go
  over native WS, not REST, so client.ts's REASON_MESSAGES never applied).
- RegisterPage: rebuilt as the real unified username-OR-phone form (not
  phone-only) -- username optional unless phone is blank, invite code
  required+validated only on the username-only path, matching the server's
  actual resolveRegistrationAccount rules. connection.ts's
  registerAccountByPhone generalized into registerAccount() supporting both
  paths, including the Tinode.credential(null) crash the old app had to
  work around on the username-only path.
- New ResetPasswordPage wired to /auth/password-reset/* (a different
  endpoint family than registration's /auth/verification-codes/*).
- Shared components: PasswordInput, VerificationCodeButton, Agreement,
  Toast.
- Fixed tinode-sdk.d.ts: the real method is getCurrentUserID(), not the
  invented getAuthenticatedUserID() -- caught live, login crashed past a
  successful auth.
- Fixed a responsive bug present on all four auth pages: fixed w-[380px]
  forms overflowed past the viewport edge below ~430px wide.

Verified end-to-end against the real backend (api.118im.com, tenant
"default"): fresh phone registration, password reset, re-login with the
new password, and the username-only path's invite-code rejection all
round-tripped correctly.

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

web/src/App.tsx

@@ -6,6 +6,7 @@ import { RequireAuth } from '@/app/RequireAuth';
 import { SectionPlaceholder } from '@/app/SectionPlaceholder';
 import { LoginPage } from '@/features/auth/LoginPage';
 import { RegisterPage } from '@/features/auth/RegisterPage';
+import { ResetPasswordPage } from '@/features/auth/ResetPasswordPage';
 import { TenantEntryPage } from '@/features/auth/TenantEntryPage';
 import { ConversationView } from '@/features/messages/ConversationView';
 import { EmptyMain } from '@/features/messages/EmptyMain';
@@ -17,6 +18,7 @@ const router = createBrowserRouter([
   { path: 'tenant', element: <TenantEntryPage /> },
   { path: 'login', element: <LoginPage /> },
   { path: 'register', element: <RegisterPage /> },
+  { path: 'reset-password', element: <ResetPasswordPage /> },
   {
     element: <RequireAuth />,
     children: [