Add component size benchmark runner, generated reports, and GitHub Action

[developit]

Motivation

• Provide automated per-component size measurement, shared-cost estimation, and Shapley attribution to help prioritize bundle-size optimizations.
• Produce a standalone HTML viewer and machine-readable artifacts so size data can be inspected and consumed by tooling.
• Integrate the measurement into CI so reports are generated on PRs and pushes and uploaded as build artifacts.

Description

• Add a new benchmark runner benchmarks/size/run-components.mjs that bundles component groups, measures raw/gzip/brotli sizes, computes shared overlaps and sampled Shapley attributions, and emits viewer + JSON/MD artifacts.
• Add generated report artifacts under benchmarks/size/results/: components.html, components.md, components.json, components.sankey.json, and components.shapley.json.
• Add a package script bench:size:components in package.json to run the new measurement (node benchmarks/size/run-components.mjs).
• Add a GitHub Actions workflow .github/workflows/component-size.yml that installs dependencies, runs pnpm bench:size:components, and uploads the generated reports as the kinu-component-size-report artifact.

Testing

• Ran the measurement via pnpm bench:size:components (invokes node benchmarks/size/run-components.mjs) which completed successfully and produced the files in benchmarks/size/results/ including components.html, components.md, and components.json.
• The CI workflow is configured to run pnpm install --frozen-lockfile and pnpm bench:size:components and to upload the artifacts; no unit tests were modified or added as part of this change.
• No automated unit/integration tests were added for the benchmarking tooling itself in this PR.

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Codex Task

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[github-actions]

Size Change: 0 B

Total Size: 37.7 kB

ℹ️ View Unchanged

Filename	Size
benchmarks/size/.tmp/few-components/bundle.css	3.03 kB
benchmarks/size/.tmp/few-components/bundle.js	637 B
benchmarks/size/.tmp/nearly-all-components/bundle.css	10.9 kB
benchmarks/size/.tmp/nearly-all-components/bundle.js	4 kB
benchmarks/size/.tmp/one-component/bundle.css	1.52 kB
benchmarks/size/.tmp/one-component/bundle.js	341 B
dist/index.css	10.9 kB
dist/index.js	6.34 kB

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