spec: Experimental switch from shiroa to typst html bundle export

[RobinJadoul]

This moves most of the pain of working with shiroa into something more under our control, and additionally gets significant compilation speed improvements.
Minimal required typst version becomes 0.15.0 because of this.

[github-actions]

Kimi Code Review

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Automated review by Kimi (Moonshot AI)

[github-actions]

Codex Code Review

• High — Bundle compilation likely fails for chips using templates. bundle.typ places every chapter in a separate document, but chip.typ queries template interaction metadata from the current document. Chapters such as CPU therefore cannot see metadata emitted by IS_BIT, IS_BYTE, etc., triggering the assertion at line 77. Make interaction counts independent of document-scoped queries or include the required metadata in every document.

• Medium — HTML equation references lose outer labels. equate-lite.typ emits label metadata only for inner labels. For an outer-labeled equation such as limbs_and_carries.typ, the replacement equation receives only <equate:revoke>, so references like @limbs:eq:decomposition become unresolved. Emit equivalent metadata/label for the only-outer case.

[RobinJadoul]

High — Bundle compilation likely fails for chips using templates.

Nope, this is fine, all things state work fine with the bundle, since it's only a single compilation emitting multiple output files.

Medium — HTML equation references lose outer labels.

The outer label is added as an inner label (but without getting an extra numbering level) because outer labels seem to not work properly in html export. The reference goes to the inner label and is as such perfectly resolved.