fix: avoid blocking async agent handlers

[wyf027]

Summary

• replace blocking HTTP calls in the Internet Computer example with aiohttp async requests
• use aiohttp for Pollinations image downloads in the payment protocol example
• move synchronous Agno knowledge search/model calls off the uAgents event loop with asyncio.to_thread

Verification

• git diff --check
• python3 -m py_compile web3/internet-computer/fetch/agent.py image-agent-payment-protocol/payment_proto.py Rag-agent/ango/agent.py

Closes #41

[gautammanak1]

@leno23, please fix the CI check

[gautammanak1]

Thanks for the contribution 🚀

The CI for this PR is currently failing. Please fix the following so we can move forward:

• format — run ruff format . and commit the result
• lint — run ruff check . --fix and resolve remaining warnings
• typecheck — fix the reported type errors
• stargazer-gate — please ⭐ star this repository (the gate passes once you've starred)

Once the checks are green it'll be ready for maintainer review. Let me know if you need any help! 🙌