style: fix PHPCS violations in PRAB emitter classes

- class-pr-core-prab-meta-reader.php: restore proper multi-line docblocks
  for all 7 class constants (WPCS requires separate summary line before @var
  tag; inline @var description fails the short-description sniff). Also fix
  return-with-assignment at is_triggered() lines (separate assign + return).
- class-pr-core-jsonld-article.php: add phpcs:ignore for
  WordPress.Security.EscapeOutput on printf($json) — wp_json_encode() is the
  canonical JSON escape; WPCS cannot trace through the intermediate variable.

No functional changes. File line counts: meta-reader 299, article 247.

Agent-Session: prcore-jsonld-remediation-20260623

includes/frontend/class-pr-core-jsonld-article.php

@@ -210,6 +210,7 @@ class PR_Core_Jsonld_Article {
 			JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT
 		);
 		if ( false !== $json ) {
+			// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- wp_json_encode() is the canonical JSON escape; no further escaping needed.
 			printf(
 				'<script type="application/ld+json">%s</script>' . "\n",
 				$json