#6116: refactor: add explicit type assertion in resolveOptionFromCommand

<!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates `resolveOptionFromCommand` (`src/cli/cli-utils.ts`) to explicitly assert the option value type (`opts[key] as T`) when walking up the commander `Command` parent chain. The behavior at runtime is unchanged; the change is purely for TypeScript typing to align the generic return type `T | undefined` with commander’s untyped `opts()` return shape. I didn’t find any new functional issues introduced by this change. In current call sites (e.g. `src/cli/models-cli.ts`), callers already treat the returned value as a string/undefined, so the assertion matches existing usage. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - The change is a narrow TypeScript-only type assertion in a helper that reads commander options; it does not alter runtime control flow or values, and current usage aligns with the asserted types. - No files require special attention <!-- greptile_other_comments_section --> **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->