Migrate e2e tests to modelcontextprotocol/go-sdk

- Update imports from mark3labs/mcp-go to modelcontextprotocol/go-sdk
- Update setupMCPClient to use CommandTransport and NewInMemoryTransports
- Convert CallToolRequest usage to CallToolParams inline style
- Update type assertions to use pointer types (*mcp.TextContent, etc.)
- Update tool slice type to []*mcp.Tool
- Update EmbeddedResource.Resource access (now *ResourceContents, not interface)
- Update consolidated tool names (issue_write, issue_read, pull_request_read, pull_request_review_write)
- Fix go-github v79 CreateTag/CreateRef API changes
- Fix commitId -> commitID naming convention
- Default to 'all' toolsets for comprehensive testing

Author: SamMorrowDrums