feat(wizards): add MiMo V2 Pro via Nous Portal as fallback provider (#447)

Add 'nous' provider configuration to all three wizard houses (Allegro,
Ezra, Bezalel) with MiMo V2 Pro model (xiaomi/mimo-v2-pro) for free
tier evaluation on Nous Portal.

- Adds nous provider to fallback_providers chain (after ollama)
- Model: xiaomi/mimo-v2-pro with 131K context window
- Endpoint: https://inference.nousresearch.com/v1
- API key env: NOUS_API_KEY
- Timeout: 120s
- Reason documented for evaluation tracking (#447)

This is the smallest concrete fix to enable Nous Portal free tier
evaluation. Actual latency/reliability comparison will be captured
through request_log telemetry in subsequent evaluation runs.

Closes #447

wizards/ezra/config.yaml

@@ -18,7 +18,13 @@ fallback_providers:
   model: gemma4:latest
   base_url: http://localhost:11434
   timeout: 300
-  reason: "Terminal fallback \u2014 local Ollama"
+  reason: Terminal fallback — local Ollama
+- provider: nous
+  model: xiaomi/mimo-v2-pro
+  base_url: https://inference.nousresearch.com/v1
+  api_key_env: NOUS_API_KEY
+  timeout: 120
+  reason: MiMo V2 Pro via Nous Portal free tier evaluation (#447)
 agent:
   max_turns: 90
   reasoning_effort: high
@@ -31,3 +37,6 @@ providers:
   openrouter:
     base_url: https://openrouter.ai/api/v1
     timeout: 120
+  nous:
+    base_url: https://inference.nousresearch.com/v1
+    timeout: 120