feat: add claude_env input for custom environment variables

Co-authored-by: ashwin-ant <ashwin-ant@users.noreply.github.com>

action.yml

@@ -41,6 +41,8 @@ inputs:
     default: ""
   mcp_config:
     description: "Additional MCP configuration (JSON string) that merges with the built-in GitHub MCP servers"
+  claude_env:
+    description: "Custom environment variables to pass to Claude Code execution (YAML format)"
     required: false
     default: ""
 
@@ -114,6 +116,7 @@ runs:
         use_bedrock: ${{ inputs.use_bedrock }}
         use_vertex: ${{ inputs.use_vertex }}
         anthropic_api_key: ${{ inputs.anthropic_api_key }}
+        claude_env: ${{ inputs.claude_env }}
       env:
         # Model configuration
         ANTHROPIC_MODEL: ${{ inputs.model || inputs.anthropic_model }}