[Feature Request]: Add missing hooks to OPA plugin

[araujof]

Description

The OPA plugin currently implements hooks for pre_invoke_tool. We should add implementations for the missing MCP hooks.

🧭 Type of Feature

Please select the most appropriate category:

• Enhancement to existing functionality
• New feature or capability
• New MCP-compliant server
• New component or integration
• Developer tooling or test improvement
• Packaging, automation and deployment (ex: pypi, docker, quay.io, kubernetes, terraform)
• Other (please describe below)

🔗 MCP Standards Check

• Change adheres to current MCP specifications
• No breaking changes to existing MCP-compliant integrations
• If deviations exist, please describe them below: