fix(typescript): add trailing commas to as const enums

[scarf005]

Summary

• add trailing commas to as const enum objects in typescript-angular, typescript-fetch, and typescript-nestjs-server
• update generated samples and add shared regression coverage

continuation of #23275

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Summary by cubic

Generate as const enum objects with trailing commas to reduce diff noise and align with common TS style across generators. Updates templates for typescript-angular, typescript-fetch, and typescript-nestjs-server, plus adds shared regression coverage.

• Bug Fixes
  • Always emit trailing commas in enum objects in typescript-angular, typescript-fetch, and typescript-nestjs-server templates.
  • Updated generated samples to reflect the new formatting.
  • Added a shared test to enforce trailing commas across TypeScript generators (including typescript-axios).

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