Fold deterministic image sizing into native image presentation

## Problem
Source pages can size and crop images with deterministic load-time scripts. Native image conversion preserves the image and container but loses the computed dimensions and transform, causing major visual drift. The Weebly TeamCard fixture demonstrates this on two 280x280 card images.

## Direction
Add a generic deterministic runtime-folding primitive that materializes source image sizing/cropping into editor-valid native image presentation. Keep product-specific script names out of core.

## Acceptance
- Team card image wells match source pixels and geometry.
- Native image blocks remain editor-valid.
- Static images that need no adjustment do not regress.
- Transformer contracts and parity fixtures pass.

## AI assistance
OpenAI gpt-5.6-sol through OpenCode analyzed the parity evidence and drafted this issue. Chris Huber remains responsible for scope and implementation decisions.

Start with the Weebly TeamCard parity fixture and the transformer contracts to understand the two 280x280 image cases and current native presentation behavior. Implement the generic deterministic runtime-folding primitive, then run the parity fixtures and contract checks; done means matching source pixels and geometry, editor-valid native image blocks, and no regression for static images.

Written by the indexing model from the issue text.