add hotbunny provider + fix domain cookie scoping in requester

New channel: hotbunny (AI-generated hentai, hotbunny.ai JSON API).
Includes thumbnail proxy (/proxy/hotbunny-thumb/) since assets.hotbunny.ai
is CF bot-managed. check.py updated to treat CF-protected format URLs as
warnings rather than errors.

requester.rs: store_response_cookies now honours the Domain attribute in
Set-Cookie headers — cookies scoped to .domain.com are registered against
the parent domain so the wreq Jar returns them for sub.domain.com requests
automatically, without per-provider workarounds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/proxies/mod.rs

@@ -42,6 +42,7 @@ pub mod spankbang;
 pub mod supjav;
 pub mod sxyprn;
 pub mod thaiporntv;
+pub mod hotbunnythumb;
 pub mod jable;
 pub mod tube8;
 pub mod thepornbunny;