docs: add OpenSpec proposal for GraphQL tools

Add comprehensive proposal for general GraphQL tools in MCP server:
- proposal.md: Problem statement and impact analysis
- tasks.md: Implementation checklist
- specs/mcp-integration/spec.md: 3 new MCP tool requirements
- specs/graphql-api/spec.md: GraphQL introspection requirement

Proposal introduces get_graphql_schema and execute_graphql_query tools
to enable AI agents to discover and interact with the GraphQL API
dynamically for complex tasks beyond dedicated member tools.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

openspec/changes/add-graphql-tools/proposal.md

@@ -0,0 +1,24 @@
+## 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