MCP server v2.26.5: Fuller whoami output and mixed-case workspace name support

Improvements

• whoami tool: Now returns the full authenticated user record, including the identity provider. This is useful for telling Sanity accounts apart when one email maps to several accounts. The authMethod field is renamed to mcpAuthMethod to clarify it describes how the MCP session authenticated, not the account's identity provider.

Fixes

• Workspace names: Schema tools no longer reject mixed-case workspace names like MyWorkspace; the published workspaceName pattern now matches Sanity Studio's workspace name rules, which allow capital letters.