v0.3.1 - ComfyUI 0.33 compatibility

0.3.1 - ComfyUI 0.33 compatibility

Fixes the crash on ComfyUI 0.33, reported in #12 by javawock7618 and #8 by
azra1l. Thanks to both for narrowing it to the exact commits.

0.33 removed frame_count from PackedLayout.__init__, along with the
first/last keyframe restriction it existed to enforce. The pack's
self-test failed against the new signature and the node refused to run,
which is the intended failure mode but not a useful one.

The patch now reads the constructor's signature and adapts to either
shape. Verified against the real upstream file at both 0.32.0
(ddbaa87) and 0.33.0 (7fe8a61): identical anchor and audio window
coordinates on either, to the last bit.

Also in this release:

• Keyframe audio latents are no longer dropped from the payload. 0.33
  lets a keyframe carry audio of its own, and rebuilding the list from
  references alone filled every audio conditioning row with the wrong
  content.
• Anchors pair with the correct rows when a stock Add Guide anchor shares
  the graph. On 0.33 an audio-only guide contributes a cond_audio
  segment and no cond segment, which the old pairing miscounted.
• The mixed keyframe guard is retired on 0.33, where stock compensates
  untagged keyframes itself. A Ref2VA graph carrying an Add Guide anchor
  is now a supported combination rather than a refusal.
• The test harness fakes both layout shapes, so both paths stay covered.

What 0.33 means for this pack

ComfyUI 0.33 added interior keyframe anchors, multi-frame guide clips and
an Add Guide for MiniMax H3 node. If all you want is to anchor a still or
a short clip at an arbitrary frame, use the stock node.

What this pack still does that stock does not: it slices the previous
clip's tail straight out of its latent with no VAE round trip, and it ends
the pinned audio window at the join rather than starting it there, which
is the difference between the model continuing your soundtrack and the
model writing something that sounds like it.

This is a compatibility release. A rebuild on 0.33's public keyframe
format, dropping the runtime patches entirely, is next.