Add PLUGIN_REPORT_IGNORE constant for internal/paid plugins

[apermo]

Summary

• Adds PLUGIN_REPORT_IGNORE constant (array or comma-separated string) to skip wp.org API lookups
• Ignored plugins show "Ignored (via config)" in the Repository column
• No API call or SVN check is made for ignored slugs
• Cached with the longer CACHE_LIFETIME_NOREPO (1 week)

Closes #14

Configuration

In wp-config.php:

define( 'PLUGIN_REPORT_IGNORE', 'yoast-seo-premium,my-internal-plugin' );

Test in WordPress Playground

Open in WordPress Playground

Pre-installed test plugins: Apermo Admin Bar (outdated), giWeather (closed/removed)

To test the ignore feature in Playground, add this to wp-config.php via the PHP console:

define( 'PLUGIN_REPORT_IGNORE', 'apermo-adminbar' );

Then clear cache and reload — Apermo Admin Bar should show "Ignored (via config)".

Test plan

• Without the constant defined, all plugins behave as before
• With PLUGIN_REPORT_IGNORE set as comma-separated string, listed plugins show "Ignored (via config)"
• With PLUGIN_REPORT_IGNORE set as array, same behavior
• Ignored plugins still show name, author, version, activation status
• Clear cache and verify ignored plugins don't trigger API calls