Improve MCP Workflow Example with Dynamic Input, Auto Model Detection…

[harshdesaii]

Description

This PR significantly improves the MCP workflow example by adding dynamic topic input, resolving model compatibility issues, and introducing automatic model selection based on available API keys. It enables seamless execution even when only a single model provider is available.

Fixes # (issue)

• Fix model initialization (model -> model_name)
• Fix typos in executor (promp, resul, inpu)
• Add dynamic topic input from user
• Add smart model selection based on available API keys