fix: merge execute load options with dir

[liyimil]

What changed

• merge execute()'s dir with partial loadOptions
• preserve explicitly supplied load options such as ignoreManifest
• normalize file URL roots before loading the CLI
• add a regression test covering dir plus {ignoreManifest: true}

Why

Passing loadOptions currently replaces dir entirely, so inferred values such as root are lost. Supplying only ignoreManifest then reaches the loader without a root and fails before the option can take effect.

Fixes #1533.

Checks

• yarn compile --noEmit
• focused Mocha test on Node 22: test/execute.test.ts
• yarn lint (passes with existing warnings)
• ESLint and Prettier checks for the changed files

Prepared with Codex assistance; the diff was reviewed and the checks above were run locally.

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @liyimil to sign the Salesforce Inc. Contributor License Agreement.

[jfeingold35]

Closed and re-opened to re-evaluate the CLA.
I will review this, conduct any necessary QA, and merge if it's ready to go. Thank you for the contribution, @liyimil.

[jfeingold35]

@liyimil , this looks like it resolves the issue where you needed to have root, but it still seems like the description is being pulled from the manifest instead of the file.