Add free Zen models: big-pickle, ring-2.6-1t-free, nemotron-3-super-free

Only free tier models that are Claude Code capable per opencode.ai Zen API.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

api/routes.py

@@ -28,7 +28,12 @@ DISCOVERED_MODEL_CREATED_AT = "1970-01-01T00:00:00Z"
 # the previous hardcoded Claude model list with the requested NVIDIA-
 # compatible models so clients only see those options.
 REQUESTED_PROVIDER_MODELS = [
+    # Zen/OpenCode free models
     "zen/minimax-m2.5-free",
+    "zen/big-pickle",
+    "zen/ring-2.6-1t-free",
+    "zen/nemotron-3-super-free",
+    # NVIDIA NIM models
     "nvidia_nim/stepfun-ai/step-3.5-flash",
     "nvidia_nim/qwen/qwen3-coder-480b-a35b-instruct",
     "nvidia_nim/mistralai/mistral-large-3-675b-instruct-2512",