fix: replace unsafe fixed-size buffers with dynamic formatting helpers; add util format helpers; centralize log_on_line cleanup

v0/token.c

@@ -124,7 +124,11 @@ TokenStream* tokenstream_open(const char* filename, const char* code) {
 		return NULL;
 	}
 
-	ts->filename = strdup(filename ? filename : "unknown");
+    const char* name_src = filename ? filename : "unknown";
+    ts->filename = malloc(strlen(name_src) + 1);
+    if (ts->filename) {
+        memcpy(ts->filename, name_src, strlen(name_src) + 1);
+    }
 	ts->code = code;
 	ts->pos = 0;
 	ts->line = 1;