Add lower-bound validation for VARCHAR size in MariaDB adapter

Throws DatabaseException when VARCHAR size is <= 0, ensuring both lower
and upper bounds are validated before returning the VARCHAR type.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: abnegate

src/Database/Adapter/MariaDB.php

@@ -1679,6 +1679,9 @@ protected function getSQLType(string $type, int $size, bool $signed = true, bool
                 return "VARCHAR({$size})";
 
             case Database::VAR_VARCHAR:
+                if ($size <= 0) {
+                    throw new DatabaseException('VARCHAR size ' . $size . ' is invalid; must be > 0. Use TEXT, MEDIUMTEXT, or LONGTEXT instead.');
+                }
                 if ($size > $this->getMaxVarcharLength()) {
                     throw new DatabaseException('VARCHAR size ' . $size . ' exceeds maximum varchar length ' . $this->getMaxVarcharLength() . '. Use TEXT, MEDIUMTEXT, or LONGTEXT instead.');
                 }