fix: V-002 security vulnerability

Initialize dfa_transitions = NULL before generate_transitions() so that
the cleanup check in regex_compile() is never reading an uninitialized
pointer when the overflow guard returns early.

Fixes -Werror=maybe-uninitialized on aarch64 GCC 13.

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

Author: orbisai0security

regex_src/regexJIT.c

@@ -1876,6 +1876,7 @@ struct regex_machine* regex_compile(const regex_char_t *regex_string, int length
 	}
 
 	/* Step 2: generating branches (Right->Left). */
+	compiler_common.dfa_transitions = NULL;
 	error_code = generate_transitions(&compiler_common);
 	stack_destroy(&compiler_common.stack);
 	stack_destroy(&compiler_common.depth);