Fix the zero-date CASE expression to compare the function call result, not the raw value

The strtr refactor accidentally changed `WHEN $function_call > '0'`
to `WHEN {value} > '0'`, comparing the wrong operand and breaking
date validation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: adamziel

wp-includes/sqlite-ast/class-wp-pdo-mysql-on-sqlite.php

@@ -5701,7 +5701,7 @@ private function cast_value_for_saving(
 						WHEN {value} IS NULL THEN NULL
 						WHEN {value} IN ('0000-00-00', '0000-00-00 00:00:00') AND NOT {reject_zero_date} THEN {zero_date_value}
 						WHEN SUBSTR({value}, 1, 4) != '0000' AND (SUBSTR({value}, 6, 2) = '00' OR SUBSTR({value}, 9, 2) = '00') AND NOT {reject_zero_in_date} THEN {value}
-						WHEN {value} > '0' THEN {function_call}
+						WHEN {function_call} > '0' THEN {function_call}
 						ELSE {fallback}
 					END",
 					array(