- add lib/router.ts with task classifier, model hint mapping, resolve fallback chain, and auto-detect defaults
- integrate auto-routing mode in conversation model selector with __auto__ option
- persist/read model defaults from localStorage (llm-model-defaults)
- route prompts to selected/routed model before streaming
- add multi-modal input controls (attach file, image, voice)
- support attachment chips, removal, drag-and-drop file attach
- add audio transcription flow via /api/whisper/transcribe and append result to input
- support sending attachments payload alongside text from InputBar