Convert MCP plugin examples to E2E tests

[adambenhassen]

Summary

The MCP plugin has example configurations in packages/plugins/mcp/examples/ that demonstrate various plugin features. These examples should be converted to actively tested E2E tests to ensure they remain functional as the plugin evolves.

Motivation

Examples that aren't actively tested tend to drift out of sync with the implementation. Converting them to E2E tests ensures they stay maintained and serve as living documentation.

Current state

• Examples exist at packages/plugins/mcp/examples/
• MCP plugin E2E tests exist at e2e/mcp-plugin/ covering core functionality
• The examples cover additional configuration patterns not yet in E2E tests

Acceptance criteria

• Each example in packages/plugins/mcp/examples/ has a corresponding E2E test
• Examples are verified to work with both node and Docker runners
• Existing example files are either converted in-place or replaced by the E2E test configs