Improve Yoast SEO integration coverage; drop obsolete fixHomeBreadcrumbs

[nlemoine]

Summary

Raises Yoast SEO integration coverage from ~56% to ~95%, and removes one method that became dead code as Yoast evolved.

New tests (WordPressSeoTest)

• Indexables::configurePageDetection (31% → 100%) — including the pre_option_show_on_front workaround, the core trick that makes Yoast resolve PFCPT pages instead of the posts page.
• Schema (58% → 100%) — the CollectionPage idempotency branch.
• WordPressSeo composite (0% → 100%) — isSupported() / registerHooks() boot.
• A fixTaxonomyBreadcrumbs guard (current taxonomy is not the post type's main taxonomy).

Removal — Breadcrumbs::fixHomeBreadcrumbs

This method only ran when Yoast's get_page_type() returned Home_Page for a PFCPT page. That held in Yoast ~17 (when the logic was first written, late 2021), but Yoast has since moved is_static_posts_page() onto the $wp_query->is_posts_page flag — which the plugin's Handler always sets — and checks it before the Home_Page branch. PFCPT pages now resolve to Static_Posts_Page, so the method is unreachable.

Verified against Yoast 25.9 and 27.7, with and without Polylang, and with breadcrumbs-home set — every combination resolves to Static_Posts_Page. Git history preserves the method if a future Yoast ever regresses.

Result

src/Integration/WordPressSeo/: Indexables / Schema / WordPressSeo at 100%, Breadcrumbs at 91% (the remaining lines are defensive early-return guards). phpcs and PHPStan clean; 12 WordPressSeoTest tests pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.34%. Comparing base (b6d0c01) to head (fe4cb84).

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #19      +/-   ##
============================================
+ Coverage     87.42%   90.34%   +2.91%     
+ Complexity      494      485       -9     
============================================
  Files            31       31              
  Lines          1336     1315      -21     
============================================
+ Hits           1168     1188      +20     
+ Misses          168      127      -41     

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