feat: add structured logging example for observability

[Aditi777613]

This PR adds a new Observability Example under examples/observability/ to demonstrate structured logging and metrics tracking using loguru.

Key Highlights:

Implements a reusable logging_config.py setup for structured JSON logs.

Adds automatic request tracing with unique request IDs.

Logs HTTP methods, status codes, and latency for each request.

Compatible with external log aggregation tools like Grafana Loki and Elastic Stack.

Tested Locally:
✅ Verified with uvicorn examples.observability.test_app:app --reload
✅ Logs display structured JSON with request-level observability

Impact:
Enhances Bindu’s observability layer, helping developers monitor agent performance and behavior in production.

[raahulrahl]

Why we need this? we are handling thorough loguru.

[Aditi777613]

Thanks for the feedback! 🙌
While Loguru is indeed already part of Bindu’s core logging setup, this example is intended to demonstrate practical observability usage — showing how developers can:

1. Enable structured JSON logs with request-level correlation IDs,
2. Measure latency and per-request metrics, and
3. Integrate with external tools like Grafana Loki or Elastic Stack.

It doesn’t modify Bindu’s internal logging — just provides a developer-facing reference example under examples/ for those looking to extend observability in their own agent apps.