build: update cross-repo angular dependencies to v21.2.8 (21.2.x)

[angular-robot]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
@angular-devkit/build-angular	21.2.7 → 21.2.8
@angular-devkit/core	21.2.7 → 21.2.8
@angular-devkit/schematics	21.2.7 → 21.2.8
@angular/build	21.2.7 → 21.2.8
@angular/cli	21.2.7 → 21.2.8
@angular/ssr	21.2.7 → 21.2.8
@schematics/angular	21.2.7 → 21.2.8

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Release Notes

angular/angular-cli (@​angular-devkit/build-angular)

v21.2.8: 21.2.8

Compare Source

@​angular/cli

Commit	Description
	dynamically resolve project Angular CLI executable inside MCP tools
	ignore EBADF file system errors during MCP project scan
	use headless option in MCP test tool

@​angular-devkit/build-angular

Commit	Description
	ensure route has leading slash in prerender builder
	fix app-shell route format and

@​angular/build

Commit	Description
	use rootDir for HMR component updates path resolution
	validate V8 coverage support for browsers in Vitest

[ngbot]

I see that you just added the action: merge label, but the following checks are still failing:
     conflicts with base branch "21.2.x"
     status "mergeability" is failing
     status "pullapprove" is pending

If you want your PR to be merged, it has to pass all the CI checks.

If you can't get the PR to a green state due to flakes or broken main, please try rebasing to main and/or restarting the CI job. If that fails and you believe that the issue is not due to your change, please contact the caretaker and ask for help.

[leonsenft]

This PR was merged into the repository. The changes were merged into the following branches:

• 21.2.x: 750af5b