Test or narrow the supported viem version range

## Problem

ABX packages declare a broad `viem` range beginning at `^2.21.0`, but the repository does not test clean consumers at the declared boundary or across later allowed releases. An allowed version can therefore introduce type incompatibilities without CI noticing.

## Desired outcome

Make the declared compatibility range an executable claim.

## Acceptance criteria

- Add clean-consumer typecheck coverage at the minimum supported version and a current allowed version, or narrow the declared range to what is actually supported.
- Cover the public SDK types as consumed outside the workspace, not only source builds using the repository lockfile.
- Document the supported range consistently across published packages.

Start by locating the published package manifests, compatibility declarations, CI configuration, and public SDK type entry points. Run the existing typechecks to understand how the workspace lockfile is used, then test clean consumers against the minimum and a current allowed viem version. Done means the supported range is tested or narrowed and documented consistently across published packages.

Written by the indexing model from the issue text.