Add privacy policy content registration

[masteradhoc]

What?

Fixes #868

Adds suggested privacy policy content for the Two Factor plugin via the WordPress Privacy Policy Guide (wp_add_privacy_policy_content).

Why?

WordPress provides a built-in mechanism for plugins to contribute suggested text to a site's privacy policy page. The Two Factor plugin stores personal data (TOTP secret keys, backup codes, enabled provider settings) but has never registered suggested privacy policy text, leaving site administrators without guidance on what to disclose.

How?

• Registers an admin_init action that calls a new static method Two_Factor_Core::add_privacy_policy_content().
• The method calls wp_add_privacy_policy_content() with a suggested block of text covering:
  • What data is stored (TOTP secret key, backup codes, email address usage, enabled providers list)
  • Who data is shared with (no one)
  • How long data is retained (for the lifetime of the user account)
  • What rights users have over their data (export and erasure)

Testing Instructions

1. Activate the Two Factor plugin on a WordPress site.
2. In the WordPress admin, go to Settings → Privacy.
3. Click Check for guide suggestions (or create/open a privacy policy page).
4. Confirm that a "Two Factor" section appears in the Privacy Policy Guide with the suggested text covering the four data categories above.
5. Confirm that the suggested text can be copied into the policy page.
6. Deactivate the plugin and confirm the section no longer appears in the guide.

Screenshots or screencast

Changelog Entry

Added - Register suggested privacy policy content via wp_add_privacy_policy_content so site administrators are guided on disclosing Two Factor authentication data.

[github-actions]

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Co-authored-by: masteradhoc <masteradhoc@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>

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[jeffpaul]

Functional approach and rationale sounds fine to me, will defer to others on technical review of implementation.