Vendor libs/hump, sfxrlua, json4lua, narrator as real files

These were committed as empty submodule gitlinks with no .gitmodules,
so the folders were never populated and the game could not load
(require of libs/hump/timer, libs/sfxrlua/sfxr, narrator.narrator).
Checked out each at its pinned commit and vendored the files, matching
the existing bundled-libs convention. Removed the junk libs/libs/ tree.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

libs/narrator/test/units/choices-sticky.ink

@@ -0,0 +1,13 @@
+-> homers_couch
+
+=== homers_couch ===
+	+	[Eat another donut]
+		You eat another donut. -> fine
+	*	[Get off the couch]
+		You struggle up off the couch to go and compose epic poetry.
+		-> END
+
+=== fine ===
+* Ok, is it fine? -> homers_couch
+* Ok, it's fine! -> homers_couch
+* -> END