Upgrade PHPStan to 2.x and raise analysis level from 6 to 10

- Bump phpstan/phpstan ^2.0 and szepeviktor/phpstan-wordpress ^2.0
- Move the analysis level into phpstan.neon (single source) and raise it to 10
- Add Val, a runtime coercion helper that narrows untyped WordPress boundary
  values (wpdb rows, REST params, superglobals, options) with explicit checks
  instead of blind casts, plus unit tests
- Type value-object fromRow() params as stdClass (what wpdb returns) and map
  columns through Val so unexpected shapes degrade safely
- Use %i identifier placeholders for table names in all wpdb::prepare() calls
  so every query string is a literal and identifiers are escaped by WordPress;
  raises the minimum WordPress version to 6.2 where %i was introduced
- Guard wpdb::prepare() null result before wpdb::query() in updateTax()
- Fix nullable get_permalink()/strtotime() handling, list types at REST and
  capability call sites, dead null-coalescing on checked superglobals, and
  narrow get_users() results before mapping
- Register Val method names with the ValidatedSanitizedInput sniff so it
  validates the real sanitizer around each superglobal read
- Update repository unit tests for the %i placeholder arguments

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Registration/QuestionRepository.php

@@ -54,8 +54,8 @@ class QuestionRepository {
 	 * @return list<Question>
 	 */
 	public function findByOffering( int $offeringId, bool $activeOnly = false ): array {
-		$sql    = "SELECT * FROM {$this->table} WHERE offering_id = %d";
-		$params = [ $offeringId ];
+		$sql    = 'SELECT * FROM %i WHERE offering_id = %d';
+		$params = [ $this->table, $offeringId ];
 
 		if ( $activeOnly ) {
 			$sql     .= ' AND is_active = %d';
@@ -71,7 +71,7 @@ class QuestionRepository {
 
 	public function findById( int $id ): ?Question {
 		$row = $this->db->get_row(
-			$this->db->prepare( "SELECT * FROM {$this->table} WHERE id = %d", $id )
+			$this->db->prepare( 'SELECT * FROM %i WHERE id = %d', $this->table, $id )
 		);
 
 		return $row ? Question::fromRow( $row ) : null;