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/runtime/save-load.lua

@@ -0,0 +1,59 @@
+local narrator, describe, it, assert = ...
+
+local content = [[
+  VAR x = 1
+  * (choice) [Hello]
+  - (hello) Hello world!
+  -> knot
+  === knot
+  = stitch
+  ~ x = 2
+  ~ temp y = 3
+  A line 1
+  A line 2
+  A line 3
+  * Just a road to hell -> END
+  * The best road to hell -> END
+]]
+
+local book = narrator.parse_content(content)
+
+local saved_state
+
+it('Saving', function()
+  local story = narrator.init_story(book)
+  story:begin()
+  story:continue()
+  story:choose(1)
+  story:continue(2)
+
+  saved_state = story:save_state()
+
+  local expected_path = { knot = 'knot', stitch = 'stitch' }
+  assert.are.same(saved_state.path, expected_path)
+  assert.equal(saved_state.variables['x'], 2)
+  assert.equal(saved_state.temp['y'], 3)
+  assert.equal(saved_state.visits._._.hello, 1)
+  assert.equal(#saved_state.output, 2)
+  assert.equal(#saved_state.paragraphs, 2)
+  assert.equal(#saved_state.choices, 2)
+end)
+
+it('Loading.', function()
+  local story = narrator.init_story(book)
+  story:begin()
+  story:load_state(saved_state)
+
+  local expected_path = { knot = 'knot', stitch = 'stitch' }
+  assert.are.same(story.current_path, expected_path)
+  assert.equal(story.variables['x'], 2)
+  assert.equal(story.temp['y'], 3)
+  assert.equal(story:get_visits('hello'), 1)
+  assert.equal(#story.output, 2)
+
+  local paragraphs = story:continue()
+  local choices = story:get_choices()
+
+  assert.equal(#paragraphs, 2)
+  assert.equal(#choices, 2)
+end)