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/Availability/AvailabilityRepository.php

@@ -116,11 +116,11 @@ class AvailabilityRepository {
 		}
 
 		$whereClause = implode( ' AND ', $where );
-		$sql         = "SELECT * FROM {$this->table} WHERE {$whereClause} ORDER BY start_dt ASC";
+		$sql         = "SELECT * FROM %i WHERE {$whereClause} ORDER BY start_dt ASC";
 
-		$rows = $params
-			? $this->db->get_results( $this->db->prepare( $sql, $params ) )
-			: $this->db->get_results( $sql );
+		$rows = $this->db->get_results(
+			$this->db->prepare( $sql, array_merge( [ $this->table ], $params ) )
+		);
 
 		return array_map( AvailabilitySlot::fromRow( ... ), $rows ?? [] );
 	}
@@ -133,7 +133,8 @@ class AvailabilityRepository {
 	public function findByInstructor( int $instructorId ): array {
 		$rows = $this->db->get_results(
 			$this->db->prepare(
-				"SELECT * FROM {$this->table} WHERE instructor_id = %d ORDER BY start_dt ASC",
+				'SELECT * FROM %i WHERE instructor_id = %d ORDER BY start_dt ASC',
+				$this->table,
 				$instructorId
 			)
 		);
@@ -149,7 +150,8 @@ class AvailabilityRepository {
 	public function findUnbookedInGroup( int $recurrenceGroup ): array {
 		$rows = $this->db->get_results(
 			$this->db->prepare(
-				"SELECT * FROM {$this->table} WHERE recurrence_group = %d AND is_booked = 0 ORDER BY start_dt ASC",
+				'SELECT * FROM %i WHERE recurrence_group = %d AND is_booked = 0 ORDER BY start_dt ASC',
+				$this->table,
 				$recurrenceGroup
 			)
 		);
@@ -159,7 +161,7 @@ class AvailabilityRepository {
 
 	public function findById( int $id ): ?AvailabilitySlot {
 		$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 ? AvailabilitySlot::fromRow( $row ) : null;