docs: fix missing imports in custom agents and graph routes examples

docs/agents/custom-agents.md

@@ -865,8 +865,10 @@ Allows an [`LlmAgent`](llm-agents.md) to treat another `BaseAgent` instance as a
 
     ```python
     # Conceptual Setup: Agent as a Tool
+    from google.adk import Event
     from google.adk.agents import LlmAgent, BaseAgent
     from google.adk.tools import agent_tool
+    from google.genai import types
     from pydantic import BaseModel
 
 

docs/graphs/routes.md

@@ -154,6 +154,10 @@ A sequential route runs each node once, in the listed order.
     `Event(route=...)` value, which the `edges` dict dispatches to different nodes.
 
     ```python
+    from google.adk import Event, Workflow
+    from google.adk.agents import Agent
+
+
     def router(node_input: str):
         """Route to task B or C based on node_input."""
         if condition(node_input):
@@ -407,6 +411,9 @@ lifecycle on each iteration.
 === "Python"
 
     ```python
+    from google.adk import Event, Workflow
+
+
     def router(node_input: str):
         """Route to task B or C based on node_input."""
         if condition(node_input):