fix: always default InlineQueryResultPhoto thumbnail to photo url

[KnightNiwrem]

Note

This PR was primarily written by GPT-5.6 Sol xhigh in ChatGPT Work.

Summary

Ensure that InlineQueryResultBuilder.photo always defaults thumbnail_url to the photo URL, including when callers supply other options.

The builder now:

• normalizes photo_url once
• sets thumbnail_url before spreading options, so an explicit thumbnail still overrides the default
• makes thumbnail_url optional in the builder's options type
• covers both defaulted and explicitly supplied thumbnails with regression tests

Why

The existing implementation puts the default thumbnail inside the default value of the entire options parameter. JavaScript only evaluates that default when options is omitted completely. Passing an object such as { caption: "cap" } therefore drops the documented default thumbnail.

This was fixed on main in #879. This PR ports the same implementation and regression coverage to v2.

Verification

• reproduced the missing thumbnail_url before the change
• deno fmt --check src/convenience/inline_query.ts test/convenience/inline_query.test.ts
• deno lint src/convenience/inline_query.ts test/convenience/inline_query.test.ts
• deno check --no-config src/convenience/inline_query.ts
• type-checked and executed a standalone probe covering both default and explicit thumbnails

[chatgpt-codex-connector]

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