feat: add NVIDIA NIM and MiniMax provider support (#552)

* 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

src/components/ProviderManager.tsx

@@ -1009,6 +1009,16 @@ export function ProviderManager({ mode, onDone }: Props): React.ReactNode {
         label: 'Custom',
         description: 'Any OpenAI-compatible provider',
       },
+      {
+        value: 'nvidia-nim',
+        label: 'NVIDIA NIM',
+        description: 'NVIDIA NIM endpoint',
+      },
+      {
+        value: 'minimax',
+        label: 'MiniMax',
+        description: 'MiniMax API endpoint',
+      },
       ...(mode === 'first-run'
         ? [
             {