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/sfxrlua/config.ld

@@ -0,0 +1,12 @@
+project = "sfxr.lua"
+description = "A port of the sfxr sound effect synthesizer to Lua"
+title = "sfxr.lua Documentation"
+format = "markdown"
+not_luadoc = true
+style = "!pale"
+kind_names = {topic = "Topics", module = "API"}
+dir = "./docs"
+
+file = "sfxr.lua"
+topics = {
+}