fix(net): join array fieldlist in net.retrieve so the documented usage works

[wmathurin]

Problem

net.retrieve's public, typed signature accepts fieldlist: string[]:

retrieve('Contact', id, ['FirstName', 'LastName'], onSuccess, onError)

But the array was passed straight through to the native bridge as the fields query param. On Android, ArrayList.toString() produces fields=[FirstName, LastName]; on iOS, NSArray's description gives a similar bracketed form. Both are rejected by Salesforce with INVALID_FIELD / 400. The only form that actually worked — a pre-joined string — contradicted the TypeScript signature. The shared test suite only ever passed a pre-joined string, so the typed string[] path was never exercised.

Credit to @james-enperso for identifying the bug and the noEmit build discrepancy in PR #475.

Fix

Join the array before it crosses the bridge. A string is passed through unchanged for backward compatibility with callers that pre-join:

const fieldsValue = Array.isArray(fieldlist) ? fieldlist.join(",") : fieldlist;
const fields = fieldsValue ? { fields: fieldsValue } : null;

Build infrastructure fix

This PR also fixes the dist/ regeneration problem identified by @james-enperso.

The root issue: tsconfig.json extends @react-native/typescript-config which sets noEmit: true, so npm run build (tsc --build) type-checks only and never regenerates dist/. The committed dist/ was CommonJS output from a separate config, meaning any change to src/ required either hand-editing dist/ (fragile) or knowing about an undocumented release-time step.

This PR adds tsconfig.build.json — a config that extends tsconfig.json but overrides noEmit: false, module: commonjs, moduleResolution: node — so dist/ can be regenerated reproducibly by anyone with tsc --project tsconfig.build.json.

setversion.sh is updated to call npx tsc --project tsconfig.build.json instead of npm run build, so the release process now produces a correct dist/ automatically.

The dist/ regeneration in this commit also picks up TypeScript version drift (?? operator replacing verbose null-coalescing patterns, class field declarations at class body level) — all functionally identical.

Test plan

• Verify net.retrieve('Contact', id, ['FirstName', 'LastName'], ...) works on iOS
• Verify net.retrieve('Contact', id, ['FirstName', 'LastName'], ...) works on Android
• Verify pre-joined string form net.retrieve('Contact', id, 'FirstName,LastName', ...) still works on both platforms
• Run tsc --project tsconfig.build.json — should produce clean dist/ with no errors

🤖 Generated with Claude Code

[github-actions]

	Tests	Passed ✅	Skipped	Failed
iOS ^18 Test Results	35 ran	35 ✅

Test	Result
No test annotations available

[github-actions]

	Tests	Passed ✅	Skipped	Failed
iOS ^26 Test Results	35 ran	35 ✅

Test	Result
No test annotations available