fix(canvas): use vertical-align: top to eliminate baseline gap (#5484)

* fix(canvas): make graph canvas block-level to eliminate baseline gap

- Change <canvas id=graph-canvas> to display:block via Tailwind class
- Removes 1–5 px baseline offset between canvas and container
- Aligns canvas and TransformPane origins; fixes link/slot endpoint drift

No behavioral changes beyond layout origin alignment; no dependent CSS relies on inline/baseline.

* switch block to align-top

* Update test expectations [skip ci]

* Revert "Update test expectations [skip ci]"

This reverts commit ee0dfd4.

* empty commit for ci

* Update test expectations [skip ci]

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Co-authored-by: github-actions <[email protected]>

Author: benceruleanlu