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/hump/spec/timer_spec.lua

@@ -0,0 +1,73 @@
+local timer = require 'timer'()
+
+describe('hump.timer', function()
+  it('runs a function during a specified time', function()
+    local delta, remaining
+
+    timer:during(10, function(...) delta, remaining = ... end)
+
+    timer:update(2)
+    assert.are.equal(delta, 2)
+    assert.are.equal(8, remaining)
+
+    timer:update(5)
+    assert.are.equal(delta, 5)
+    assert.are.equal(3, remaining)
+
+    timer:update(10)
+    assert.are.equal(delta, 10)
+    assert.are.equal(0, remaining)
+  end)
+
+  it('runs a function after a specified time', function()
+    local finished1 = false
+    local finished2 = false
+
+    timer:after(3, function(...) finished1 = true end)
+    timer:after(5, function(...) finished2 = true end)
+
+    timer:update(4)
+    assert.are.equal(true, finished1)
+    assert.are.equal(false, finished2)
+
+    timer:update(4)
+    assert.are.equal(true, finished1)
+    assert.are.equal(true, finished2)
+  end)
+
+  it('runs a function every so often', function()
+    local count = 0
+
+    timer:every(1, function(...) count = count + 1 end)
+
+    timer:update(3)
+    assert.are.equal(3, count)
+
+    timer:update(7)
+    assert.are.equal(10, count)
+  end)
+
+  it('can script timed events', function()
+    local state
+
+    timer:script(function(wait)
+      state = 'foo'
+      wait(1)
+      state = 'bar'
+    end)
+
+    assert.are.equal('foo', state)
+    timer:update(0.5)
+    assert.are.equal('foo', state)
+    timer:update(1)
+    assert.are.equal('bar', state)
+  end)
+
+  it('cancels and clears timer functions', function()
+    pending('to be tested...')
+  end)
+
+  it('tweens', function()
+    pending('to be tested...')
+  end)
+end)