fix(open-8974): detect all tool types in Google ADK agent traces

[viniciusdsmello]

Summary

• Fixes tool detection in extract_agent_attributes for Google ADK tracing, which was missing raw function tools and failing to unwrap AgentTool instances
• Adds _extract_tool_info() helper that handles all three ADK tool types: raw callables, BaseTool subclasses, and AgentTool (agent-as-a-tool pattern)
• AgentTool entries now include type: "agent_tool" and recursively expose the wrapped agent's own tools via agent_tools

Root Cause

The extract_agent_attributes function checked hasattr(tool, "name") to detect tools, but ADK stores raw Python functions in agent.tools — functions use __name__, not name. This caused all plain function tools to be silently skipped. Additionally, AgentTool wrappers were never unwrapped to discover the inner agent's tools.

Before (broken)

{
  "tools": [
    {"name": "WeatherAgent", "description": "..."},
    {"name": "CalculatorAgent", "description": "..."}
  ]
}

• Direct function tools (e.g. get_current_time) missing entirely
• No visibility into wrapped agent's own tools

After (fixed)

{
  "tools": [
    {"name": "get_current_time", "description": "Returns the current time."},
    {
      "name": "WeatherAgent",
      "type": "agent_tool",
      "description": "...",
      "agent_tools": [
        {"name": "get_weather", "description": "Retrieves weather..."}
      ]
    },
    {
      "name": "CalculatorAgent",
      "type": "agent_tool",
      "description": "...",
      "agent_tools": [
        {"name": "calculate", "description": "Evaluates math..."}
      ]
    }
  ]
}

Test plan

• Verify orchestrator pattern: direct tools + AgentTool-wrapped sub-agents all visible
• Verify standalone agents with only function tools are detected
• Verify mixed sub_agents + AgentTool pattern works correctly
• Integration test with valid API keys to confirm end-to-end trace data

Closes OPEN-8974

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