## Why

The current MCP server provides dedicated tools for member management (`list_members`, `get_member`, `create_member`, `update_member`). While these work well for basic operations, they are limited for complex tasks that require:
- Flexible querying with custom field selection
- Complex filters or relationships (future)
- Ad-hoc data exploration by AI agents
- Leveraging GraphQL's full introspection capabilities

AI agents connected via the MCP server should be able to discover the GraphQL schema dynamically and construct their own queries for complex tasks.

## What Changes

- Add `get_graphql_schema` tool to expose the complete GraphQL schema via introspection
- Add `execute_graphql_query` tool to allow AI agents to execute arbitrary GraphQL queries and mutations
- Update README.md with documentation for the new tools
- Keep existing dedicated member tools for backward compatibility and simple operations

## Impact

- Affected specs: `mcp-integration`, `graphql-api`
- Affected code: `src/mcp_server.py`, `README.md`
- Breaking changes: None (additive only)
- The dedicated member tools remain available, providing a simpler interface for common operations
- AI agents gain flexibility to handle complex queries without requiring new dedicated tools