* feat: add NVIDIA NIM and MiniMax provider support
- Add nvidia-nim and minimax to --provider CLI flag
- Add model discovery for NVIDIA NIM (160+ models) and MiniMax
- Update /model picker to show provider-specific models
- Fix provider detection in startup banner
- Update .env.example with new provider options
Supported providers:
- NVIDIA NIM: https://integrate.api.nvidia.com/v1
- MiniMax: https://api.minimax.io/v1
* fix: resolve conflict in StartupScreen (keep NVIDIA/MiniMax + add Codex detection)
* fix: resolve providerProfile conflict (add imports from main, keep NVIDIA/MiniMax)
* fix: revert providerSecrets to match main (NVIDIA/MiniMax handled elsewhere)
* fix: add context window entries for NVIDIA NIM and new MiniMax models
* fix: use GLM-5 as NVIDIA NIM default and MiniMax-M2.5 for consistency
* fix: address remaining review items - add GLM/Kimi context entries, max output tokens, fix .env.example, revert to Nemotron default
* fix: filter NVIDIA NIM picker to chat/instruct models only, set provider-specific API keys from saved profiles
* chore: add more NVIDIA NIM context window entries for popular models
* fix: address remaining non-blocking items - fix base model, clear provider API keys on profile switch
