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/1-1.txt

@@ -0,0 +1,10 @@
+We boarded the train, but where?
+
+>) First class
+2) Travel in the guard's van
+
+I settled my master.
+
+>) Move to third class
+
+I put myself in third.

libs/narrator/test/units/stitches/2.txt

@@ -0,0 +1,6 @@
+We boarded the train, but where?
+
+1) First class
+>) Travel in the guard's van
+
+Whoosh..