feat(models): add DeepSeek model configurations

Add configurations for DeepSeek-V3 and DeepSeek-Chat models
via OpenRouter integration.

- DeepSeek-V3: Reasoning model (input: /usr/bin/bash.27, output: .10)
- DeepSeek-Chat: Chat model (input: /usr/bin/bash.14, output: /usr/bin/bash.28)

Fixes #215

eval/configs/models/deepseek-chat.yaml

@@ -0,0 +1,13 @@
+model: deepseek-ai/deepseek-chat
+provider: openrouter
+cost:
+  input: 0.14  # per 1M tokens
+  output: 0.28  # per 1M tokens
+  
+# Native DeepSeek API (direct)
+api_key: null
+base_url: null
+
+# For OpenRouter, uncomment below and comment out direct config above
+# api_key: \${OPENROUTER_API_KEY}
+# base_url: https://openrouter.ai/api/v1

eval/configs/models/deepseek-v3.yaml

@@ -0,0 +1,15 @@
+model: deepseek-ai/DeepSeek-V3
+provider: openrouter
+cost:
+  input: 0.27  # per 1M tokens
+  output: 1.10  # per 1M tokens
+  
+# Native DeepSeek API (direct)
+# Get your API key at: https://platform.deepseek.com/
+# Or use OpenRouter with: OPENROUTER_API_KEY
+api_key: null
+base_url: null
+
+# For OpenRouter, uncomment below and comment out direct config above
+# api_key: \${OPENROUTER_API_KEY}
+# base_url: https://openrouter.ai/api/v1