feat(array): add arrFlatMap with ES5 polyfill

[nev21]

• Add arrFlatMap and polyArrFlatMap implementations with one-level flatten behavior for mapped values.
• Introduce ArrFlatMapCallbackFn type for array and array-like callback signatures.
• Export arrFlatMap and the callback type from public index and polyfills entry points.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.44%. Comparing base (53d481f) to head (9094157).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #533      +/-   ##
==========================================
+ Coverage   98.86%   99.44%   +0.58%     
==========================================
  Files         140      141       +1     
  Lines        4147     4181      +34     
  Branches      892      922      +30     
==========================================
+ Hits         4100     4158      +58     
+ Misses         47       23      -24     

Files with missing lines	Coverage Δ
lib/src/array/callbacks.ts	100.00% <ø> (+50.00%)	⬆️
lib/src/array/flatMap.ts	100.00% <100.00%> (ø)
lib/src/array/flatten.ts	100.00% <ø> (ø)
lib/src/polyfills.ts	94.11% <100.00%> (+41.05%)	⬆️

... and 3 files with indirect coverage changes

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[Copilot]

Pull request overview

Adds arrFlatMap (with polyArrFlatMap) to @nevware21/ts-utils, extending the Array helper surface with an ES5-compatible flatMap implementation and public exports.

Changes:

• Added arrFlatMap helper and polyArrFlatMap polyfill implementation.
• Introduced ArrFlatMapCallbackFn type and exported it from the main index.
• Added common tests, updated polyfills entry/export wiring, and adjusted bundle size thresholds/docs.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/src/array/flatMap.ts	New arrFlatMap wrapper + polyArrFlatMap implementation.
lib/src/array/callbacks.ts	Adds ArrFlatMapCallbackFn type for flatMap callbacks.
lib/src/index.ts	Exports arrFlatMap and ArrFlatMapCallbackFn publicly.
lib/src/polyfills.ts	Registers flatMap in prototype polyfill installation and exports polyArrFlatMap.
lib/src/array/flatten.ts	Updates docs to reference arrFlatMap for map-then-flatten workflows.
lib/test/src/common/array/flatMap.test.ts	Adds coverage for arrFlatMap, polyArrFlatMap, and export wiring.
lib/test/bundle-size-check.js	Increases bundle size thresholds for ES5 minified artifacts.
.size-limit.json	Updates size-limit thresholds for built ES5/ES6 modules.
docs/feature-backlog.md	Updates backlog entry related to arrFlatMap (currently with a content issue).

[nevware21-bot]

Approved by nevware21-bot

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

[nevware21-bot]

Approved by nevware21-bot

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

[nevware21-bot]

Approved by nevware21-bot