refactor: [IEG-2929] Replace fp-ts with vanilla ts in CGN

[LeleDallas]

Short description

This pull request focuses on simplifying the codebase by removing unnecessary functional programming dependencies (such as fp-ts's Option, Either, and pipe) and replacing them with more idiomatic and straightforward TypeScript code.

List of changes proposed in this pull request

• Replaced uses of fp-ts's Option, Either, and pipe with native TypeScript constructs and simplified conditional logic
• Updated saga tests to remove fp-ts constructs, using plain objects for responses and errors, and adjusted assertions accordingly
• Simplified and clarified error handling by throwing and catching native Error objects instead of wrapping them in Either or custom types, and using a consistent approach for network and generic errors.

How to test

Ensure CGN flow has no regression in all screens

[github-actions]

PR Title Validation for conventional commit type

✅ All good! PR title follows the conventional commit type.

[github-actions]

Jira Pull Request Link

This Pull Request refers to Jira issues:

• IEG-2929

[codecov]

Codecov Report

❌ Patch coverage is 85.55556% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.95%. Comparing base (aad67c0) to head (6b5b82f).

Files with missing lines	Patch %	Lines
...pp/ts/features/bonus/cgn/store/reducers/details.ts	40.00%	3 Missing ⚠️
...p/ts/features/bonus/cgn/hooks/useSpecialCtaCgn.tsx	0.00%	2 Missing ⚠️
...ga/networking/activation/getBonusActivationSaga.ts	75.00%	1 Missing and 1 partial ⚠️
...etworking/eyca/activation/getEycaActivationSaga.ts	93.54%	1 Missing and 1 partial ⚠️
...ts/features/bonus/cgn/components/CgnWalletCard.tsx	50.00%	0 Missing and 1 partial ⚠️
...res/bonus/cgn/components/merchants/utils/index.tsx	85.71%	0 Missing and 1 partial ⚠️
...a/orchestration/activation/handleActivationSaga.ts	0.00%	0 Missing and 1 partial ⚠️
...n/screens/merchants/CgnMerchantsListByCategory.tsx	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8246      +/-   ##
==========================================
+ Coverage   62.77%   62.95%   +0.17%     
==========================================
  Files        1952     1952              
  Lines       37085    37085              
  Branches     6205     6205              
==========================================
+ Hits        23280    23346      +66     
+ Misses      12419    12358      -61     
+ Partials     1386     1381       -5     

Files with missing lines	Coverage Δ
...cgn/components/detail/eyca/EycaDetailComponent.tsx	100.00% <100.00%> (ø)
...nus/cgn/components/merchants/ModuleCgnDiscount.tsx	100.00% <100.00%> (+7.14%)	⬆️
...features/bonus/cgn/saga/networking/bucket/index.ts	95.23% <100.00%> (ø)
...gn/saga/networking/categories/cgnCategoriesSaga.ts	100.00% <100.00%> (ø)
...n/saga/networking/details/getCgnInformationSaga.ts	100.00% <100.00%> (ø)
...working/eyca/activation/getEycaActivationStatus.ts	100.00% <100.00%> (ø)
.../cgn/saga/networking/eyca/details/getEycaStatus.ts	92.85% <100.00%> (ø)
...a/networking/merchants/cgnGetMerchantsCountSaga.ts	100.00% <100.00%> (ø)
...cgn/saga/networking/merchants/cgnMerchantDetail.ts	100.00% <100.00%> (ø)
...ga/networking/merchants/cgnOfflineMerchantsSaga.ts	100.00% <100.00%> (ø)
... and 15 more

---

Continue to review full report in Codecov by Harness.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update aad67c0...6b5b82f. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.