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/visits.lua

@@ -0,0 +1,65 @@
+local narrator, describe, it, assert = ...
+
+local content = [[
+  A root text
+  + Go to knot -> knot
+  === knot
+  + Go to stitch -> stitch
+  = stitch
+  + Go to label -> label
+  - (label) Some text
+  + (choice) Go to root -> _._
+]]
+
+local book = narrator.parse_content(content)
+local story = narrator.init_story(book)
+
+story:begin()
+
+local function visits()
+  local visits = {
+    root = story:get_visits(''),
+    knot = story:get_visits('knot'),
+    stitch = story:get_visits('knot.stitch'),
+    label = story:get_visits('knot.stitch.label'),
+    choice = story:get_visits('knot.stitch.choice')
+  }
+
+  return visits
+end
+
+local places = { 'root', 'knot', 'stitch', 'label' }
+
+for cycle = 1, 3 do
+  describe('Visits with cycle ' .. cycle .. '.', function()
+    story:continue()
+
+    for place_index = 1, #places do
+      local place = places[place_index]
+
+      it('Visit the ' .. place .. '.', function()
+        story:continue()
+
+        local place = place
+        local divert = story.choices[1].divert
+
+        local expected_root = cycle
+        local expected_knot = place_index > 1 and cycle or cycle - 1
+        local expected_stitch = place_index > 2 and cycle or cycle - 1
+        local expected_label = place_index > 3 and cycle or cycle - 1
+        local expected_choice = place_index > 4 and cycle or cycle - 1
+
+        local visits = visits()
+
+        assert.equal(visits.root, expected_root)
+        assert.equal(visits.knot, expected_knot)
+        assert.equal(visits.stitch, expected_stitch)
+        assert.equal(visits.label, expected_label)
+        assert.equal(visits.choice, expected_choice)
+
+        story:choose(1)
+      end)
+    end
+
+  end)
+end