fix(build): replace @vercel/ncc with esbuild to support @actions/core v3

[Copilot]

@actions/core v3 is ESM-only (drops CJS exports), which breaks @vercel/ncc since its underlying webpack bundler can't resolve the import-only exports field.

Changes

• Remove @vercel/ncc — incompatible with ESM-only dependencies
• Add esbuild — handles ESM natively, bundles to CJS for the node20 Actions runner
• Update build script:

  "build": "esbuild src/action.ts --bundle --platform=node --target=node20 --format=cjs --outfile=dist/index.js"

• Rebuild dist/index.js with the new bundler

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 3118a4d

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[secaccount]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[lavoiesl]

Merging this in #38 to test them together