fix(phpcs): move ignore pragmas into file-level docblocks

File-level sniffs like WordPress.Files.FileName are evaluated at the file level,
not at code level. They require phpcs:ignore directives to be placed within the
file-level docblock (/** ... */), not in code comments.

Moved all 81 phpcs:ignore pragmas from code comments to the file-level docblocks.
This applies to:
- 79 class files with class-naming convention ignores
- prautoblogger.php with strict-types docblock ignore
- uninstall.php with strict-types docblock ignore

includes/admin/class-metrics-page.php

@@ -1,8 +1,9 @@
 <?php
-// phpcs:ignore WordPress.Files.FileName.InvalidClassFileName -- class naming convention differs from WordPress standard
 declare(strict_types=1);
 
 /**
+ * phpcs:ignore WordPress.Files.FileName.InvalidClassFileName -- class naming convention differs from WordPress standard
+ *
  * Admin page displaying cost dashboard, content scores, and generation history.
  *
  * Shows: monthly spend, daily cost chart, spend by pipeline stage, budget