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/Auth/InstructorController.php

@@ -3,6 +3,8 @@ declare(strict_types=1);
 
 namespace Unsupervised\Schedular\Auth;
 
+use Unsupervised\Schedular\Val;
+
 /**
  * Studio-admin **Instructors** page: create instructor accounts and toggle each
  * instructor's managed capabilities. Gated on `manage_instructors`. A studio
@@ -24,7 +26,7 @@ class InstructorController {
 		}
 
 		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only instructor selector.
-		$instructorId = absint( $_GET['instructor_id'] ?? 0 );
+		$instructorId = absint( Val::int( $_GET['instructor_id'] ?? 0 ) );
 		$instructor   = $instructorId > 0 ? get_userdata( $instructorId ) : false;
 
 		if ( $instructor && in_array( RoleManager::INSTRUCTOR, (array) $instructor->roles, true ) ) {
@@ -50,12 +52,15 @@ class InstructorController {
 				'email'      => $user->user_email,
 				'registered' => $user->user_registered,
 			],
-			get_users(
-				[
-					'role'    => RoleManager::INSTRUCTOR,
-					'orderby' => 'display_name',
-					'order'   => 'ASC',
-				]
+			array_filter(
+				get_users(
+					[
+						'role'    => RoleManager::INSTRUCTOR,
+						'orderby' => 'display_name',
+						'order'   => 'ASC',
+					]
+				),
+				static fn( mixed $user ): bool => $user instanceof \WP_User
 			)
 		);
 
@@ -66,7 +71,7 @@ class InstructorController {
 	private function handleFormAction(): string {
 		// Nonce is verified by the caller (renderPage) before this method runs.
 		// phpcs:disable WordPress.Security.NonceVerification.Missing
-		$action = sanitize_key( wp_unslash( $_POST['usc_action'] ?? '' ) );
+		$action = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ?? '' ) ) );
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
 		if ( 'create' === $action ) {
@@ -82,8 +87,8 @@ class InstructorController {
 
 	private function createInstructor(): string {
 		// phpcs:disable WordPress.Security.NonceVerification.Missing
-		$email = sanitize_email( wp_unslash( $_POST['email'] ?? '' ) );
-		$name  = sanitize_text_field( wp_unslash( $_POST['display_name'] ?? '' ) );
+		$email = sanitize_email( Val::string( wp_unslash( $_POST['email'] ?? '' ) ) );
+		$name  = sanitize_text_field( Val::string( wp_unslash( $_POST['display_name'] ?? '' ) ) );
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
 		if ( ! is_email( $email ) ) {
@@ -125,8 +130,9 @@ class InstructorController {
 
 	private function updateCaps(): string {
 		// phpcs:disable WordPress.Security.NonceVerification.Missing
-		$instructorId = absint( $_POST['instructor_id'] ?? 0 );
-		$submitted    = array_map( 'sanitize_key', (array) wp_unslash( $_POST['capabilities'] ?? [] ) );
+		$instructorId = absint( Val::int( $_POST['instructor_id'] ?? 0 ) );
+		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- each capability key is sanitized with sanitize_key() in the array_map callback.
+		$submitted = array_values( array_map( static fn( mixed $cap ): string => sanitize_key( Val::string( $cap ) ), (array) wp_unslash( $_POST['capabilities'] ?? [] ) ) );
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
 		$instructor = $instructorId > 0 ? get_userdata( $instructorId ) : false;