update .md with latest two-factor changes / requirements

[masteradhoc]

What?

Updates AGENTS.md and TESTS.md to reflect recent changes to the plugin so the internal docs stay in sync with the actual codebase.
Fixes #

Why?

The two docs had drifted out of date:

• AGENTS.md didn't mention the new settings class/page (Settings → Two-Factor), the two-factor.php registration of the site-wide enabled-providers filters, or the two_factor_enabled_providers option and its constant.
• TESTS.md referenced an outdated test class name (Tests_Two_Factor_Core) instead of the current Test_ClassTwoFactorCore, and was missing coverage notes for nonce validation on password-reset notices, profile settings UI output, and site-wide option cleanup on uninstall.

Keeping these contributor-facing docs accurate reduces confusion for anyone (human or AI-assisted) onboarding to the codebase or writing new tests.

How?

• In AGENTS.md: expanded the two-factor.php bullet to mention it loads the settings class and registers the enabled-providers filter callbacks; added a new settings/class-two-factor-settings.php bullet; added a "Key Site Options" table documenting ENABLED_PROVIDERS_OPTION_KEY / two_factor_enabled_providers.
• In TESTS.md: corrected the test class name from Tests_Two_Factor_Core to Test_ClassTwoFactorCore in both the command example and class description; added bullets covering password-reset nonce validation, profile settings UI output, and uninstall cleanup of site-wide options.

No functional/code changes — documentation only.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude
Model(s): Claude Sonnet 5
Used for: Drafting the documentation updates to AGENTS.md and TESTS.md; reviewed and edited by me before submission.

Testing Instructions

This is a documentation-only change with no functional impact. Verify by reading through AGENTS.md and TESTS.md and confirming they accurately describe the current codebase:

1. Check that the settings page, filter hooks, and two_factor_enabled_providers option described in AGENTS.md match two-factor.php and settings/class-two-factor-settings.php.
2. Check that the Test_ClassTwoFactorCore class name in TESTS.md matches tests/class-two-factor-core.php.
3. Confirm npm run composer -- test -- --filter Test_ClassTwoFactorCore runs the core test suite correctly.

Screenshots or screencast

Not applicable — documentation-only change, no UI.

Changelog Entry

Development Update - Updated AGENTS.md and TESTS.md to reflect the settings page, enabled-providers option, and corrected test class references.

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

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