test: add regression tests for CSV query serialization (#28)

[aditya226-sharma]

Summary

Adds regression tests for array/comma-separated query option serialization in endpoint methods.

Changes

• Added new test block "serializes array options as comma-separated query values"
• Tests movies.images with include_image_language: ["en", "null"] → serialized as en,null
• Tests movies.details with append_to_response: ["credits", "videos", "images"] → serialized as credits,videos,images
• Tests tvShows.images with include_image_language: ["en"] → serialized as en
• Uses the existing mocked request capture pattern (no live TMDB requests)

Why

Array and comma-separated query options are a common source of serialization bugs. These tests establish regression coverage for the csv() utility's integration with endpoint methods.

Closes #28

[TDanks2000]

Looks good overall, but there’s one issue in the movies.details test.

movies.details() expects the append-to-response values as the second argument directly, so this:

tmdb.movies.details(550, {
	append_to_response: ["credits", "videos", "images"],
})

should be:

tmdb.movies.details(550, ["credits", "videos", "images"])

The current version doesn’t match the method signature and should fail typechecking/runtime.

Once that’s fixed and bun run test + bun run typecheck pass, this should be good to merge.