Sergejomon feat/typescript angular 21

[wing328]

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Summary by cubic

Adds Angular 21 support to the TypeScript Angular generator, sets 21.0.0 as the default, and adds v21 samples plus CI coverage. This lets users generate Angular 21 clients with the right peer and tooling versions.

• New Features

  • Support Angular 21 in typescript-angular (docs updated to 9.x–21.x).
  • Default ngVersion updated to 21.0.0.
  • Added Angular 21 dependency map: TypeScript >=5.9<6, rxjs 7.4.0, ng-packagr 21.0.0, zone.js 0.15.0.
  • New configs and generated Petstore samples: v21 and v21-provided-in-root.
  • CI workflow watches the new v21 sample paths.

• Migration

  • To generate Angular ≤20 clients, set additionalProperties.ngVersion to 20.0.0 in your config.

^{Written for commit d8252d6. Summary will update on new commits.}