Add Live Debugger consumer build canary

[watson]

Summary

• add a target-neutral yarn cli canary <target> framework for external consumer builds
• add an initial web-ui target covering both primary and Module Federation Rspack builds
• compare paired control and Live Debugger-instrumented builds without custom include or exclude filters
• validate emitted JavaScript and Live Debugger instrumentation, and report build-time plus raw/gzip bundle-size deltas
• write a versioned JSON report with provenance and preserve safe cleanup of temporary package links
• document target discovery, execution, metrics, artifacts, and failure behavior

Follow-up plan

The CLI in this PR is the execution foundation, not the intended long-term manual workflow. Follow-up PRs will:

• run each canary target and phase automatically on a recurring schedule in trusted CI
• submit compatibility status and the control/instrumented build-time and bundle-size measurements to Datadog using stable, low-cardinality tags
• add a Datadog dashboard that graphs build-time and raw/gzip bundle-size overhead over time, split by target and build phase
• retain CI reports and logs for failed builds so regressions can be investigated without reproducing them locally

Once this automation is in place, contributors should only need the local CLI to develop or troubleshoot the canary itself.

Verification

• yarn format
• yarn typecheck:all
• yarn cli integrity
• yarn test:unit packages/tools/src/commands/canary
• yarn cli canary web-ui