Repair embedded dependency build and test setup

Isolate vendored test registration, namespace project error codes, and update dependency revisions. Fix mutable sprite path handling, out-of-tree fixtures, and charviewer initialization while documenting the outstanding character-to-sprite refcount bug.

Co-authored-by: Codex (GPT-5) <noreply@openai.com>

tests/staticstring.c

@@ -1,5 +1,6 @@
 #include <string.h>
 #include <akerror.h>
+#include <akgl/error.h>
 #include <akgl/heap.h>
 #include <akgl/staticstring.h>
 
@@ -111,7 +112,7 @@ akerr_ErrorContext *test_akgl_string_initialize(void)
 	FAIL_NONZERO_BREAK(errctx, strcmp((char *)&ptr->data, "Test value"), AKERR_VALUE, "Expected 'Test value', got %s", (char *)&ptr->data);
 
     	CATCH(errctx, akgl_heap_release_string(NULL));
-	FAIL_BREAK(errctx, AKERR_BEHAVIOR, "Failure to properly handle NULL pointer");
+	FAIL_BREAK(errctx, AKGL_ERR_BEHAVIOR, "Failure to properly handle NULL pointer");
     } CLEANUP {
     } PROCESS(errctx) {
     } FINISH(errctx, true);