release(v3): [1/4] Modernize repository to align with actions/typescript template

[lasith-kg]

📚 PR Train

This PR is part of a stacked PR train delivering the v3 release. Review/merge bottom-up in order:

#	PR	Change	Base
1	👉 #170 (this PR)	Modernize repository to actions/typescript (ESM + Node 24)	main
2	#171	Add support for return_run_details	release/v3-1-node-24
3	#172	Remove dead error handling code	release/v3-2-dispatch-workflow
4	#173	v3 release (combined → main)	main

⚠️ PRs 1–3 are stacked (each targets the one above). PR #173 is the combined branch that actually merges into main.

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Realigns the repo with GitHub's current actions/typescript-action template, used as the reference for this refactor — a tooling/build modernization with no change to the action's runtime behavior.

Highlights

• Node 24 runtime — action.yml bumped node20 → node24 (requires runners with Node 24).
• Native ESM + Rollup — project converts to ESM and swaps the @vercel/ncc bundler for Rollup.
• Dropped uuid — now uses Node's built-in crypto.randomUUID.
• Tooling refresh — flat ESLint config, updated Prettier/tsconfig/Jest, tests moved to __tests__/, new check-dist.yml CI check.

No changes to inputs, outputs, or dispatch logic.