fix: pass correct pointer to cleanup in ensure_vector_match error path

When the second vector fails to parse in ensure_vector_match(), the cleanup function for the first vector was called with 'a' (void**) instead of '*a' (void*). This caused sqlite3_free to be called with a stack address instead of the heap-allocated vector, resulting in a crash:                    
                                                                                                                                                                                                                                                                                                                                                                   
    malloc: Non-aligned pointer being freed                                                                                                                                                                           
    Fatal error 6: Aborted                                                                                                                                                                                            
                                                                                                                                                                                                                      
The fix dereferences the pointer correctly, matching how cleanup is done in other error paths.

Author: renatgalimov

sqlite-vec.c

@@ -1,4 +1,4 @@
-#include "sqlite-vec.h"
+f#include "sqlite-vec.h"
 
 #include <assert.h>
 #include <errno.h>
@@ -1016,7 +1016,7 @@ int ensure_vector_match(sqlite3_value *aValue, sqlite3_value *bValue, void **a,
   if (rc != SQLITE_OK) {
     *outError = sqlite3_mprintf("Error reading 2nd vector: %s", error);
     sqlite3_free(error);
-    aCleanup(a);
+    aCleanup(*a);
     return SQLITE_ERROR;
   }