feat(web/m7-user-mgmt): /settings expansion + /forgot-password (U3-T5a)

Lands four of the U3 frontend surfaces. Splits T5 because the
dispatch covering everything in one shot crashed the runtime
mid-execution; this is the salvageable half.

- /settings gains three cards alongside Appearance: Profile
  (display name + email), Password (current + new + confirm with
  client-side mismatch check), API Token (display + copy +
  regenerate-with-double-click-confirm). Server error codes map
  to clear toasts.
- /forgot-password — public; takes an email and always shows the
  success message regardless of whether the email is on file
  (mirrors the server's no-enumeration posture).
- Login page gets a "Forgot password?" link below the existing
  register link.
- API client functions for the four /me endpoints (changePassword,
  updateProfile, getAPIToken, regenerateAPIToken), the SMTP admin
  trio (getSMTPConfig, updateSMTPConfig, testSMTPConfig), and the
  forgot/reset auth pair (forgotPassword, resetPassword).

Tests for these surfaces + /reset-password page + admin SMTP card
land in T5b (next follow-up).

web/src/lib/api/queries.ts

@@ -40,6 +40,7 @@ export const qk = {
   coverProviders:         ()              => ['coverProviders'] as const,
   adminUsers:             ()              => ['adminUsers'] as const,
   adminInvites:           ()              => ['adminInvites'] as const,
+  smtpConfig:             ()              => ['smtpConfig'] as const,
   suggestions:            (limit?: number) =>
     ['suggestions', { limit: limit ?? 12 }] as const,
   home:         ()                 => ['home'] as const,