Docs/improve transports and renderers

[jeevanjoseph03]

Title: docs: add code examples for transports and renderers

Description:

Changes

Filled in missing TODO sections in the documentation:

• docs/transports.md: Added code examples for HTTP/REST, WebSockets, and SSE.
• docs/renderers.md: Added Quickstart guides for Lit, Angular, and Flutter.

Verification

Verified code examples against existing patterns in samples/client.