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-conditional.ink

@@ -0,0 +1,17 @@
+-> door
+
+=== door ===
+*   { not france.paris } [Go to Paris] -> france.paris
+*   { not england.london } [Go to London] -> england.london
+*   { france || england } [Go home]
+    Sweet home... -> END
+
+=== france ===
+= paris
+Hello Paris!
+-> door
+
+=== england ===
+= london
+Hello London!
+-> door