Add RandomAdviceAgent with example usage

[shaheensyed06]

Overview:
This PR introduces a small agent called RandomAdviceAgent:

Returns a random piece of advice when pinged.

Includes a simple example to demonstrate usage.

Motivation:

Demonstrates how new agents can be easily created and plugged into Bindu.

Shows initiative by adding a simple, fun, and useful agent.

Aligns with the Bindu philosophy of building first and pushing half-built ideas forward.

Implementation Details:

File: agents/random_advice_agent.py

Class: RandomAdviceAgent

Method: ping(message=None) → returns a random advice from a predefined list.

Example usage included at the bottom of the file:

if name == "main":
agent = RandomAdviceAgent()
print("Ping agent...")
print("Agent says:", agent.ping())