List agent prompts

# Get authentication token
PHENOML_TOKEN=$(curl -X POST "https://experiment.app.pheno.ml/v2/auth/token" \
  -u "$PHENOML_CLIENT_ID:$PHENOML_CLIENT_SECRET" \
  | jq -r '.access_token')

curl -X GET "https://experiment.app.pheno.ml/agent/prompts/list" \
  -H "Authorization: Bearer $PHENOML_TOKEN"

{
  "success": true,
  "message": "Prompts retrieved successfully",
  "prompts": [
    {
      "id": "prompt_123",
      "name": "Medical Assistant System Prompt",
      "description": "System prompt for medical assistant agent",
      "content": "You are a helpful medical assistant...",
      "is_default": false,
      "tags": [
        "medical",
        "system"
      ]
    },
    {
      "id": "prompt_456",
      "name": "Clinical Coding Prompt",
      "description": "Prompt for ICD-10 / SNOMED coding tasks",
      "content": "You assist with mapping clinical text to standard codes...",
      "is_default": false,
      "tags": [
        "coding"
      ]
    }
  ]
}