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/Booking/BookingRepository.php

@@ -80,7 +80,7 @@ class BookingRepository {
 
 	public function findById( int $id ): ?Lesson {
 		$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 ? Lesson::fromRow( $row ) : null;
@@ -96,12 +96,14 @@ class BookingRepository {
 
 		$rows = $this->db->get_results(
 			$this->db->prepare(
-				"SELECT l.* FROM {$this->table} l
-                 JOIN {$avTable} a ON a.id = l.slot_id
+				'SELECT l.* FROM %i l
+                 JOIN %i a ON a.id = l.slot_id
                  WHERE l.instructor_id = %d
                    AND l.status != %s
                    AND a.start_dt >= %s
-                 ORDER BY a.start_dt ASC",
+                 ORDER BY a.start_dt ASC',
+				$this->table,
+				$avTable,
 				$instructorId,
 				Lesson::STATUS_CANCELLED,
 				current_time( 'mysql' )
@@ -119,11 +121,13 @@ class BookingRepository {
 
 		return (int) $this->db->get_var(
 			$this->db->prepare(
-				"SELECT COUNT(*) FROM {$this->table} l
-                 JOIN {$avTable} a ON a.id = l.slot_id
+				'SELECT COUNT(*) FROM %i l
+                 JOIN %i a ON a.id = l.slot_id
                  WHERE l.student_id = %d
                    AND l.status != %s
-                   AND a.start_dt >= %s",
+                   AND a.start_dt >= %s',
+				$this->table,
+				$avTable,
 				$studentId,
 				Lesson::STATUS_CANCELLED,
 				current_time( 'mysql' )
@@ -139,7 +143,8 @@ class BookingRepository {
 	public function findByStudent( int $studentId ): array {
 		$rows = $this->db->get_results(
 			$this->db->prepare(
-				"SELECT * FROM {$this->table} WHERE student_id = %d ORDER BY created_at DESC",
+				'SELECT * FROM %i WHERE student_id = %d ORDER BY created_at DESC',
+				$this->table,
 				$studentId
 			)
 		);
@@ -157,11 +162,13 @@ class BookingRepository {
 
 		$rows = $this->db->get_results(
 			$this->db->prepare(
-				"SELECT l.* FROM {$this->table} l
-                 JOIN {$avTable} a ON a.id = l.slot_id
+				'SELECT l.* FROM %i l
+                 JOIN %i a ON a.id = l.slot_id
                  WHERE l.status != %s
                    AND a.start_dt >= %s
-                 ORDER BY a.start_dt ASC",
+                 ORDER BY a.start_dt ASC',
+				$this->table,
+				$avTable,
 				Lesson::STATUS_CANCELLED,
 				current_time( 'mysql' )
 			)