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 <[email protected]>

src/Auth/RegistrationPage.php

@@ -8,6 +8,7 @@ use Unsupervised\Schedular\Policy\Policy;
 use Unsupervised\Schedular\Policy\PolicyAcceptance;
 use Unsupervised\Schedular\Policy\PolicyRepository;
 use Unsupervised\Schedular\Policy\PolicyVersionRepository;
+use Unsupervised\Schedular\Val;
 
 class RegistrationPage {
 
@@ -21,7 +22,7 @@ class RegistrationPage {
 	/**
 	 * Renders the student registration shortcode output.
 	 *
-	 * @param array<string, string> $atts Shortcode attributes (unused — reserved for future options).
+	 * @param array<string> $atts Shortcode attributes (unused — reserved for future options).
 	 */
 	public function render( array $atts ): string { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
 		if ( is_user_logged_in() ) {
@@ -29,7 +30,7 @@ class RegistrationPage {
 		}
 
 		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- token identifies the invite; the form submit is nonce-checked below.
-		$token = sanitize_text_field( wp_unslash( $_REQUEST['us_invite'] ?? '' ) );
+		$token = sanitize_text_field( Val::string( wp_unslash( $_REQUEST['us_invite'] ?? '' ) ) );
 		// Only the token's hash is stored, so hash the submitted token for lookup.
 		$invite = '' !== $token ? $this->invites->findByToken( Invite::hashToken( $token ) ) : null;
 
@@ -64,12 +65,12 @@ class RegistrationPage {
 		}
 
 		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only token used only to build the redirect target.
-		$token = sanitize_text_field( wp_unslash( $_GET['us_invite'] ?? '' ) );
+		$token = sanitize_text_field( Val::string( wp_unslash( $_GET['us_invite'] ?? '' ) ) );
 		if ( '' === $token ) {
 			return;
 		}
 
-		$pageId = (int) get_option( RegistrationController::OPTION_PAGE, 0 );
+		$pageId = Val::int( get_option( RegistrationController::OPTION_PAGE, 0 ) );
 		if ( $pageId <= 0 || is_page( $pageId ) ) {
 			return;
 		}
@@ -90,15 +91,16 @@ class RegistrationPage {
 		// The submit nonce is verified by the caller (render) before this runs.
 		// phpcs:disable WordPress.Security.NonceVerification.Missing
 		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- passwords must not be sanitized.
-		$password    = (string) wp_unslash( $_POST['password'] ?? '' );
-		$displayName = sanitize_text_field( wp_unslash( $_POST['display_name'] ?? '' ) );
+		$password    = Val::string( wp_unslash( $_POST['password'] ?? '' ) );
+		$displayName = sanitize_text_field( Val::string( wp_unslash( $_POST['display_name'] ?? '' ) ) );
 
 		if ( strlen( $password ) < 8 ) {
 			return esc_html__( 'Please choose a password of at least 8 characters.', 'unsupervised-schedular' );
 		}
 
 		$policyForms = $this->signupPolicies();
-		$accepted    = array_map( 'absint', (array) ( $_POST['accept'] ?? [] ) );
+		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.MissingUnslash, WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- each element is coerced to a positive int in the array_map callback; slashes cannot survive integer coercion.
+		$accepted = array_map( static fn( mixed $v ): int => absint( Val::int( $v ) ), (array) ( $_POST['accept'] ?? [] ) );
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
 		foreach ( $policyForms as $form ) {
@@ -141,7 +143,7 @@ class RegistrationPage {
 	 */
 	private function recordAcceptances( array $policyForms, int $userId ): void {
 		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- IP is stored verbatim for audit.
-		$ip = sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ?? '' ) );
+		$ip = sanitize_text_field( Val::string( wp_unslash( $_SERVER['REMOTE_ADDR'] ?? '' ) ) );
 
 		foreach ( $policyForms as $form ) {
 			$this->acceptances->insert(