Remove pull_image + list_registries; mark Gruppen 6+7 as entfällt

DSM methods for SYNO.Docker.Image/pull and SYNO.Docker.Registry/get
did not behave as expected in production testing against the NAS.
Tools deregistered, modules deleted, tests removed, CLAUDE.md updated.
Tool count: 19 → 17.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp_synology_container/server.py

@@ -31,7 +31,6 @@ def create_server(config: AppConfig, client: DsmClient) -> FastMCP:
     from mcp_synology_container.modules.images import register_images
     from mcp_synology_container.modules.networks import register_networks
     from mcp_synology_container.modules.projects import register_projects
-    from mcp_synology_container.modules.registries import register_registries
     from mcp_synology_container.modules.system import register_system
 
     register_projects(mcp, config, client)
@@ -40,7 +39,6 @@ def create_server(config: AppConfig, client: DsmClient) -> FastMCP:
     register_images(mcp, config, client)
     register_system(mcp, config, client)
     register_networks(mcp, config, client)
-    register_registries(mcp, config, client)
 
     logger.info("MCP server configured with all tool modules")
     return mcp