Feat: Add application passwords expiry

[DarkMatter-999]

This PR introduces the ability to set and manage expiration dates for Application Passwords in WordPress. Currently, application passwords are permanent until revoked; this change enhances security by allowing users to define a "Time to Live" (TTL) for specific credentials.

Key Changes:

• User Interface: Added an "Expires on" date picker to the "Add New Application Password" form.
• Management: Added an "Expires" column to the Application Passwords list table.
• Inline Editing: Implemented AJAX-powered inline editing for expiration dates directly from the list table, including "Save" and "Cancel" functionality.
• REST API: Updated the application-passwords controller to support the expires field for both creation and updates.
• Authentication: Updated wp_authenticate_application_password to validate the expiration timestamp. If a password has expired, authentication will fail with an application_password_expired error.
• Tests: Added e2e tests and unit tests to cover creation with expiration, inline editing of expiration dates, and ensuring expired passwords display correctly.

application_password_expiry.mp4

Trac ticket: https://core.trac.wordpress.org/ticket/53995

Use of AI Tools

AI assistance: Yes
Tool(s): Gemini/Antigravity
Model(s): Gemini 3 Flash, Gemini 3.1 Pro
Used for: Troubleshooting E2E test failures and drafting the PR description based on provided code diffs.

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