New providers: assemblyai, baidu, blackboxai, brave, cartesia, deepgram,
elevenlabs, exa, iflytek, lmsys, playht, pollinations, serper, siliconflow,
stability, tavily. Registered in mod.rs and registry.rs.
Adds a Providers tab to the admin UI with a ProviderIcon component and
catalog route. Updates backend, streaming, config, and test infrastructure
to align with the expanded provider set. Bumps all crate versions to 0.9.0.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
whit3rabbit
