Fix: 404 pages returning 200 OK with frontpage in Multisite

[Copilot]

WordPress Multisite enables use_verbose_page_rules by default, causing non-existent pages to return 200 OK with frontpage content instead of proper 404 responses.

Changes

• Disable use_verbose_page_rules in init hook (priority 1) to override WordPress/Multisite defaults
• Ensures correct 404 behavior regardless of permalink structure
• Requires rewrite flush after deployment: wp rewrite flush or save permalink settings

Technical Details

The root cause: WordPress validates page existence before accepting rewrite matches. With verbose page rules enabled, failed matches fall back to frontpage with empty query_vars and 200 status.

Setting use_verbose_page_rules = false generates more specific rewrite rules that fail properly when pages don't exist, triggering correct 404 responses.

add_action('init', function () {
    global $wp_rewrite;
    $wp_rewrite->use_verbose_page_rules = false;
}, 1);

Test Plan

• Visit non-existent URL (e.g., /this/page/does/not/exist) → verify 404
• Visit valid pages (single and hierarchical) → verify still work
• Flush rewrite rules after deployment

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