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/cases.lua

@@ -0,0 +1,78 @@
+--
+-- Test cases
+
+local runtime = {
+  'continue',
+  'observing',
+  'binding',
+  'set-get',
+  'visits',
+  'tags',
+  'jumping',
+  'save-load'
+}
+
+local units = {
+  'inclusions',
+  'comments',
+  'knots',
+  'stitches',
+
+  'text-line',
+  'text-lines',
+  'text-tags',
+  'text-glue',
+
+  'choices-basic',
+  'choices-tags',
+  'choices-conditional',
+  'choices-sticky',
+  'choices-fallback',
+  'choices-tunnel',
+
+  'labels-choices',
+  'labels-nested',
+
+  'branching',
+  'nesting',
+  'gather',
+  'loop',
+  'vars',
+  'constants',
+  'expressions',
+  'queries',
+
+  'conditions-inline',
+  'alts-inline',
+  'conditions-switch',
+  'alts-blocks',
+
+  'lists-basic',
+  'lists-operators',
+  'lists-queries',
+
+  'tunnels',
+  'escape',
+  'functions'
+}
+
+local stories = {
+  -- No complex stories at the moment
+}
+
+local cases = {
+  runtime = runtime,
+  units = units,
+  stories = stories
+}
+
+local folder_separator = package.config:sub(1, 1)
+for folder_name, folder_cases in pairs(cases) do
+  local items_with_foldes = { }
+  for _, case in ipairs(folder_cases) do
+    table.insert(items_with_foldes, folder_name .. folder_separator .. case)
+  end
+  cases[folder_name] = items_with_foldes
+end
+
+return cases