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/stitches.ink

@@ -0,0 +1,16 @@
+We boarded the train, but where?
+*	[First class] -> the_orient_express.in_first_class
+*	[Travel in the guard's van]
+	-> the_orient_express.in_the_guards_van
+
+=== the_orient_express ===
+= in_first_class
+	I settled my master.
+	*	[Move to third class]
+		-> in_third_class
+
+= in_third_class
+	I put myself in third.
+
+= in_the_guards_van
+	Whoosh..