feat(builders): keep prebuilt entry points out of the TypeScript program

[Aukevanoost]

Adapter half of native-federation/native-federation-core#122 — sharedMappings
libraries being evaluated twice at runtime (NG0201).

Why

The duplication is structural in ngtsc: metadata derived from source never carries
bestGuessOwningModule, so a synthesized reference to a path-mapped library falls
through to RelativePathStrategy and emits a deep relative import, which bypasses the
bundler's external list. The fix on the core side is to let a mapping point at a
library's build output instead of its source:

// tsconfig.json
"@org/ui": ["./dist/ui"]   // instead of ["./libs/ui/src/public-api.ts"]

With the library's .d.ts outside the app's TypeScript program, AbsoluteModuleStrategy
succeeds and the import is emitted bare. Verified end-to-end: the second copy disappears
from the app bundle and the federated chunk becomes the only one.

What this changes

Such an entry point is already-compiled JS. esbuild loads it through the linker like any
dependency, but listing it in the federation tsconfig's files makes ngtsc reject it:

TS6504: File 'dist/ui/fesm2022/ui.mjs' is a JavaScript file. Did you mean to enable
the 'allowJs' option? The file is in the program because: Root file specified for compilation

Core now marks every entry point 'source' or 'package', so updateFederationTsConfig
filters on a decision core already made rather than inferring one here from a file
extension.

Compatibility

Not a breaking change. Exposes and source mappings are both 'source', so the emitted
files array is identical for every setup that exists today — only the new prebuilt shape
is filtered out. A host whose mappings are all prebuilt still falls back to the app's own
entry points, so the program is never empty.

Worth noting this is the only adapter change the feature needs. The generic esbuild adapter
already resolves .mjs/.js entry points and never constructs a TypeScript program, so it
works with prebuilt mappings untouched — this is Angular-specific because ngtsc is.

Blocked on

@softarc/native-federation with EntryPoint.kind. The ~4.5.0 pin means the core release
has to land first; draft until then.

Testing

pnpm test 201 passing (2 new), typecheck and lint clean. Also exercised against a real
Angular 22 workspace with one mapping repointed at dist.