feat(spaces): implement Phase 6 API Layer

Implements API layer for Information Spaces:
- GraphQL schema types for spaces, documents, variables
- GraphQL queries and mutations for space operations
- CLI command group with all space management commands
- Resolver functions connecting GraphQL to SpaceService
- 38 unit tests for API components

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

markitect/graphql/__init__.py

@@ -2,11 +2,39 @@
 GraphQL interface for MarkiTect - Issue #9
 
 This package provides a GraphQL read interface for querying MarkiTect's
-database content including Markdown files, ASTs, and schemas.
+database content including Markdown files, ASTs, schemas, and Information Spaces.
 """
 
 from .schema import schema
 from .server import GraphQLServer, GraphQLClient
 from .resolvers import Query, Mutation
 
-__all__ = ['schema', 'GraphQLServer', 'GraphQLClient', 'Query', 'Mutation']
+# Space schema extensions
+from .space_schema import (
+    InformationSpaceType,
+    SpaceDocumentType,
+    SpaceVariableType,
+    SpaceQuery,
+    SpaceMutation,
+    CreateSpacePayload,
+    UpdateSpacePayload,
+    DeleteSpacePayload,
+)
+
+__all__ = [
+    # Core schema
+    'schema',
+    'GraphQLServer',
+    'GraphQLClient',
+    'Query',
+    'Mutation',
+    # Space types
+    'InformationSpaceType',
+    'SpaceDocumentType',
+    'SpaceVariableType',
+    'SpaceQuery',
+    'SpaceMutation',
+    'CreateSpacePayload',
+    'UpdateSpacePayload',
+    'DeleteSpacePayload',
+]