Transitions between presets

A preset switch dissolves rather than cuts. Nothing about it is preset-authored today — duration and blend kind are engine policy in code — but two consequences reach your file:

• Your preset renders live from the dissolve’s second frame. It is composited through its own background + post chain the whole way, so a trails accumulation starts from empty at the switch, not from the outgoing preset’s history.
• ink_* / paper_* crossfade. There is one ink pass for the blended frame, so its params travel from the outgoing preset’s values to yours across the dissolve. A preset whose look depends on ink reaches it about a second after the switch.

Per-preset [transition] declarations are a deliberate follow-up, not a gap you can work around from the TOML.

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