v0.4.0 - ComfyUI 0.34.0, patches removed

Requires ComfyUI 0.34.0 or newer. Use 0.3.1 on anything older.

ComfyUI now places keyframe anchors at any frame itself, so the two
runtime patches this pack carried are gone. Nothing in ComfyUI is
modified any more.

• patch_layout.py and patch_payload.py removed. The node builds plain
  keyframe dicts and hands them to stock code.
• layout_contract.py added. It proves, once before the first render,
  that anchors sit where the arithmetic says and that the pinned audio
  window is placed literally from a fractional, negative anchor index.
  No stock node can produce such an index, so nothing upstream tests it,
  and an integer cast added later would move the pinned sound silently.
  If a check fails the node refuses and names what moved.
• The pinned audio is a keyframe rather than a reference block. A Ref2VA
  graph's reference list is left untouched.
• Add Guide for MiniMax H3 anchors survive alongside a chained head,
  including ones carrying their own audio. Guides landing inside the
  pinned head are dropped with a warning, as first_frame anchors are.
• Other packs may patch the layout without this one standing down, since
  it no longer competes for that code. If it finds the constructor
  wrapped it says who by and checks the behaviour anyway.
• Anchor and audio window coordinates are identical to 0.3.1, verified
  against the real upstream layout on both shapes.