Optimized signing key creation and access-token management

Working with API credentials in the dashboard has been smoothed out:

• Faster signing-key creation — Creating a new signing key from the signing-keys page is noticeably faster end-to-end.
• Access tokens filtered by status — The Access tokens page now lets you toggle between active and revoked tokens so you can review either set without leaving the page.
• Signing-keys popup fix — Fixed issues with the signing-keys modal where the popup did not close after creation or did not return focus to the trigger button.
• Login activity — The “delete login activity” action was removed, and editing your password now records a clean new login entry so the security history stays accurate.