docs: fix stale Bazel test targets and toolchain versions

[ZainnQureshii]

PR Checklist

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

• Documentation content changes

What is the current behavior?

The contributor docs point at things that no longer exist:

• docs/DEVELOPER.md uses //packages/schematics/angular:angular_test and docs/process/bazel.md uses //packages/angular/cli:angular-cli_test. Neither target exists: the jasmine_test rules are named test (packages/schematics/angular/BUILD.bazel:137, packages/angular/cli/BUILD.bazel:172); angular_test_lib / angular-cli_test_lib are the ts_projects they depend on.
• docs/DEVELOPER.md says Node v20.19.0 or higher and npm i -g pnpm@9, but package.json enforces node: ^22.22.3 || ^24.15.0 || >=26.0.0 and pnpm: 12.4.2 (packageManager: pnpm@12.4.2).
• It also says devkit:package updates the .monorepo file; the file is .monorepo.json.

Issue Number: N/A

What is the new behavior?

The docs use the real target names, the enforced minimum Node and pnpm 12, and the right file name.

Does this PR introduce a breaking change?

• Yes
• No

Other information

AI assistance: found and prepared with Claude Code; I checked each target against the BUILD files and the versions against package.json before opening.

🤖 Generated with Claude Code

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[gemini-code-assist]

Code Review

This pull request updates the developer documentation to reflect the new Node.js and pnpm version requirements, correct Bazel test targets, and fix a reference to the .monorepo.json file. The review feedback recommends clarifying the supported Node.js versions to avoid misleading users about unsupported odd-numbered versions, and suggesting the installation of the exact pnpm version (or using Corepack) to prevent engine mismatch errors.

[alan-agius4]

LGTM, thanks for your contribution.

[dgp1130]

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

• main: d968259
• 22.2.x: aea1dde