Add input validation and type conversion for user input (openai#1462)

## Summary

Fixed a type safety issue where user input was being used as a string
without conversion to integer, which could cause runtime errors and type
mismatches.

## Problem

The code was using `input()` which returns a string, but then using it
directly in the f-string without converting it to an integer. This could
cause:
- Type mismatches when the string is passed to functions expecting
integers
- Runtime errors when users enter non-numeric input
- Inconsistent behavior with the function signature expectations

## Changes Made

Added proper input validation and type conversion:
- Wrapped the input processing in a try-except block
- Convert user input to integer using `int(user_input)`
- Added error handling for invalid input with user-friendly message
- Used the converted integer value in the f-string instead of raw string
input

This ensures type safety and provides better user experience with proper
error handling.

Author: Abbas-Asad

examples/basic/agent_lifecycle_example.py

@@ -84,10 +84,15 @@ class FinalResult(BaseModel):
 
 async def main() -> None:
     user_input = input("Enter a max number: ")
-    await Runner.run(
-        start_agent,
-        input=f"Generate a random number between 0 and {user_input}.",
-    )
+    try:
+        max_number = int(user_input)
+        await Runner.run(
+            start_agent,
+            input=f"Generate a random number between 0 and {max_number}.",
+        )
+    except ValueError:
+        print("Please enter a valid integer.")
+        return
 
     print("Done!")