Generate and analyse esbuild bundle metadata

[mbg]

Modifies the esbuild script to write bundle metadata to disk and adds a small script to print the bundle sizes. The script is run at the end of the build process. We can extend this in the future to provide more detailed insights.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Environments:

• Testing/None - This change does not impact any CodeQL workflows in production.

How did/will you validate this change?

• Other - Please provide details.

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Development/testing only - This change cannot cause any failures in production.

How will you know if something goes wrong after this change is released?

• Other - Please provide details.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull request overview

This PR extends the build tooling to generate esbuild metafile output on disk and adds a small pr-checks utility script to print bundle sizes, enabling easier tracking of bundle growth over time.

Changes:

• Enable esbuild metafile generation and write the metafile to meta.json during build.mjs.
• Add pr-checks/bundle-metadata.ts and run it at the end of npm run build to print output sizes.
• Refactor pr-checks GitHub API client construction into a shared api-client.ts module.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pr-checks/sync-checks.ts	Switches to a shared API client helper.
pr-checks/api-client.ts	New shared Octokit client type + constructor.
pr-checks/config.ts	Adds a constant for the esbuild metafile path.
pr-checks/bundle-metadata.ts	New script that reads the metafile and prints bundle sizes.
build.mjs	Enables esbuild metafile output and writes it to disk.
package.json	Runs the bundle-metadata script at the end of the build.
.gitignore	Ignores the generated meta.json file.

[Copilot]

The shebang #!/usr/bin/env npx tsx is not a valid /usr/bin/env invocation on many systems (because of the space). If this script is intended to be executable directly (as the require.main === module guard suggests), switch to a portable shebang (e.g. #!/usr/bin/env -S npx tsx where supported, or #!/usr/bin/env tsx and document the dependency), or remove the shebang if it will only ever be run via npx tsx ....

Suggested change

	#!/usr/bin/env npx tsx
	#!/usr/bin/env -S npx tsx