Add i18n support for password reset flow (follow-up to #3185)

[llpingll]

Describe your changes

As discussed with @ajhollid :

• Temporarily hardcoded the new strings to resolve persistent en.json conflicts during review/merge feat: Allow all users to change password (not just admins) #3185.
• Now restoring proper i18n support by extracting those strings back into en.json.

Changes:

• Replaces hardcoded strings in ForgotPassword.jsx, CheckEmail.jsx, and PasswordPanel.jsx with i18n strings.
• Adds the following new keys to en.json:
  • "accountPassword": "Go back to Account Password",
  • "forgotPassword": "Forgot password?"
  • "resetPassword": "Reset password"
  • "sessionExpired": "Your session has expired, please log in again to continue."
  • "passwordRequirements": "New password must contain at least 8 characters and must have at least one uppercase letter, one lowercase letter, one number and one special character."

No functional changes — UI/behavior is identical to the merged version, just now fully translatable.

Write your issue number after "Fixes "

Fixes #3185

Please ensure all items are checked off before requesting a review. "Checked off" means you need to add an "x" character between brackets so they turn into checkmarks.

• (Do not skip this or your PR will be closed) I deployed the application locally.
• (Do not skip this or your PR will be closed) I have performed a self-review and testing of my code.
• I have included the issue # in the PR.
• I have added i18n support to visible strings (instead of <div>Add</div>, use):

const { t } = useTranslation();
<div>{t('add')}</div>

• I have not included any files that are not related to my pull request, including package-lock and package-json if dependencies have not changed
• I didn't use any hardcoded values (otherwise it will not scale, and will make it difficult to maintain consistency across the application).
• I made sure font sizes, color choices etc are all referenced from the theme. I don't have any hardcoded dimensions.
• My PR is granular and targeted to one specific feature.
• I ran npm run format in server and client directories, which automatically formats your code.
• I took a screenshot or a video and attached to this PR if there is a UI change.

[Br0wnHammer]

@llpingll Can you please take care of the conflicts in the PR?