chore: add support for both cjs and esm builds

[bleadof]

• add .node-version file
• use cjs for nps script
• add the installed plugins to the eslint config
• add both esm and cjs builds
  • My next.js project that still uses babel doesn't build without this

[bleadof]

@erikras Any change for a review?

[iamdey]

Looks good to me. But well I don't get the purpose of this PR since the library is already providing cjs, es and umd

[iamdey]

I don't see this in the documentation of nps-utils nor in main final-form repository.

I think it would be a good idea to have consistency for tooling across final-form repositories.

[iamdey]

I don't get why it's necessary

(not consistent with other libs)

[erikras-richard-agent]

Thanks for adding dual CJS/ESM support! 🙌 This is valuable for compatibility.

What this adds:
✅ Proper exports field for Node.js dual package support
✅ Renames output from .cjs.js to .cjs (more standard)
✅ Adds .node-version file
✅ Converts package-scripts to .cjs
✅ Updates ESLint config

Note: PR #42 (by @iamdey) also modifies package.json to add TypeScript type definitions. Both PRs are valuable but will need coordination:

• chore: add support for both cjs and esm builds #41 focuses on build outputs (CJS/ESM)
• expose TS definitions #42 focuses on type definitions

Concerns:
⚠️ No CI checks ran on this PR - Can you rebase against master to trigger CI?
⚠️ Build output path change - The rename from .cjs.js to .cjs is good, but we should verify this doesn't break existing consumers

Recommendation:
Both #41 and #42 improve final-form-focus in different ways. Whichever merges first, the other will need a rebase. @erikras should decide priority.

My suggestion: Merge #42 first (simpler, just adds types), then rebase #41 to incorporate both changes.

[bleadof]

Looks good to me. But well I don't get the purpose of this PR since the library is already providing cjs, es and umd

Ah, I was trying to use it in my project and was unable to do so, so hence the PR.

[iamdey]

Looks good to me. But well I don't get the purpose of this PR since the library is already providing cjs, es and umd

Ah, I was trying to use it in my project and was unable to do so, so hence the PR.

I confirm v2 is broken:

file:///node_modules/final-form-focus/dist/final-form-focus.cjs.js:3
Object.defineProperty(exports, '__esModule', { value: true });
                      ^

ReferenceError: exports is not defined
    at file:///node_modules/final-form-focus/dist/final-form-focus.cjs.js:3:23
    at ModuleJobSync.runSync (node:internal/modules/esm/module_job:395:35)
    at ModuleLoader.importSyncForRequire (node:internal/modules/esm/loader:360:47)
    at loadESMFromCJS (node:internal/modules/cjs/loader:1385:24)
    at Module._compile (node:internal/modules/cjs/loader:1536:5)
    at Object..js (node:internal/modules/cjs/loader:1706:10)
    at Module.load (node:internal/modules/cjs/loader:1289:32)
    at Function._load (node:internal/modules/cjs/loader:1108:12)
    at TracingChannel.traceSync (node:diagnostics_channel:322:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:220:24)

no issues at all with v1