Adds two CI signals for keeping the published packages small and broadly compatible:
- Bundle size: size-limit file-mode config across packages plus a
CopilotChat import-size regression signal (gzip) so growth in the
headline consumer entrypoint is visible on every PR. A bundle-size
workflow comments results on the PR (Phase 1: no hard-fail).
- ES compatibility: a compat-check (es-check) script across 9 packages
with a root .browserslistrc, validating built .mjs/.cjs against the
es2022 build target.
The measure script is importable (measureBundle) and unit-tested. Dev
docs live under dev-docs/ (bundle-size.md, browser-compat.md). All
action refs are pinned to full commit SHAs for supply-chain safety.
David McKay