Prevent tsconfig exclusions from bypassing TypeScript security scans

[alxxjohn]

Motivation

• Fix a false negative where a repository-controlled tsconfig.json/jsconfig.json could narrow the compiler roots and cause semantic security rules to be skipped for otherwise-in-scope files.
• Ensure the scanner continues to use CodeGuard's already-filtered corpus as the TypeScript program roots while still applying project compiler options.

Description

• Change internal/codeguard/checks/support/typescript_semantic_runner_core.js to use the runner-provided corpus (input.source_files) as compiler rootNames when available and retain parsed compiler options from the config, preventing project config from removing corpus files from semantic scanning.
• Remove the configuredRootNames helper and its intersection behavior so corpus roots are not restricted by parsed.fileNames.
• Update internal/codeguard/checks/support/typescript_semantic_test.go by renaming the regression test to TestTypeScriptSemanticRunnerUsesCorpusDespiteConfiguredFiles and adjusting assertions to require that each corpus SourceFiles entry appears in the compiler roots reported by the fake TypeScript runtime.

Testing

• Ran go test ./internal/codeguard/checks/support and the package tests passed.
• Ran go test ./... across the repository and all tests passed.
• Ran git diff --check to validate there are no whitespace or diff issues and it reported no problems.

---

Codex Task