Use reCAPTCHA v3 on password reset (#135)

## Summary
- Closes #134.
- Password reset loads reCAPTCHA v3 and sends `grecaptcha.execute(siteKey, { action: 'password_reset' })` as `recaptchaToken`.
- Removes `react-google-recaptcha`. That package is a v2 widget, and the Hesychia key is v3, so Google rejected the site key on https://hesychia.ai/password_reset/ before submit.
- Site key stays `6LfENu4qAAAAAFtPejcrP3dwBDxcRPjqi7RhytJJ`. The backend already checks the v3 token with `CAPTCHA_SECRET_KEY` and rejects a score under 0.5.

## Test plan
- [x] `CI=true npm test -- --watchAll=false --coverage=false --testPathPattern=pages/PasswordReset` (6 passed)
- [ ] After deploy, open https://hesychia.ai/password_reset/ and confirm the invalid reCAPTCHA error is gone
- [ ] Submit a real account email and confirm the reset email sends
- [ ] Submit again with a bad or blocked client and confirm the page shows "Unable to reset password"

Reviewed-on: #135

llm-fe/package.json

@@ -92,11 +92,9 @@
     "@types/lodash": "~4.17.13",
     "@types/react": "^18.3.16",
     "@types/react-dom": "^18.3.5",
-    "@types/react-google-recaptcha": "^2.1.9",
     "@types/react-syntax-highlighter": "^15.5.13",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
-    "react-google-recaptcha": "^3.1.0",
     "typescript": "^4.9.5"
   },
   "overrides": {