Add pull_image + list_registries; remove Gruppe 5 (no Volume API)

- pull_image: SYNO.Docker.Image/pull with repository+tag split via
  rpartition; polls image list every 3 s until image appears, 120 s timeout
- list_registries: SYNO.Docker.Registry/get; shows name, URL, active marker
- Gruppe 5 (Volumes) removed from roadmap — SYNO.Docker.Volume does not exist
- CLAUDE.md: tool count 17 → 19, Volumes section removed
- 28 tests all passing

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

tests/test_modules/test_images.py

@@ -1,6 +1,6 @@
 """Tests for modules/images.py."""
 
-from unittest.mock import AsyncMock
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
@@ -491,3 +491,140 @@ async def test_check_image_updates_for_project():
     result = await tools["check_image_updates"](project_name="myapp")
     assert "myapp" in result
     assert "nginx:1.24" in result
+
+
+# ──────────────────────────────────────────────────────────────────────────────
+#  pull_image
+# ──────────────────────────────────────────────────────────────────────────────
+
+PULLED_IMAGE = {
+    "id": "sha256:dddd",
+    "repository": "postgres",
+    "tags": ["17.8"],
+    "size": 80 * 1024 * 1024,
+    "created": 1700000000,
+    "upgradable": False,
+}
+
+
+@pytest.mark.asyncio
+async def test_pull_image_success():
+    from mcp_synology_container.modules.images import register_images
+
+    client = AsyncMock()
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image" and method == "pull":
+            return {}
+        if api == "SYNO.Docker.Image" and method == "list":
+            return {"images": [PULLED_IMAGE]}
+        return {}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_images(mcp, make_config(), client)
+
+    with patch("asyncio.sleep", new=AsyncMock()):
+        result = await tools["pull_image"]("postgres:17.8")
+
+    assert "Pulled postgres:17.8" in result
+    assert "MiB" in result
+
+
+@pytest.mark.asyncio
+async def test_pull_image_no_tag_defaults_to_latest():
+    from mcp_synology_container.modules.images import register_images
+
+    client = AsyncMock()
+    found_image = {**PULLED_IMAGE, "repository": "nginx", "tags": ["latest"]}
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image" and method == "pull":
+            # Verify tag defaults to "latest"
+            assert kwargs.get("params", {}).get("tag") == "latest"
+            return {}
+        if api == "SYNO.Docker.Image" and method == "list":
+            return {"images": [found_image]}
+        return {}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_images(mcp, make_config(), client)
+
+    with patch("asyncio.sleep", new=AsyncMock()):
+        result = await tools["pull_image"]("nginx")
+
+    assert "Pulled nginx:latest" in result
+
+
+@pytest.mark.asyncio
+async def test_pull_image_registry_prefixed():
+    """Registry-prefixed images (e.g. ghcr.io/foo/bar:v1) split at last ':'."""
+    from mcp_synology_container.modules.images import register_images
+
+    client = AsyncMock()
+    found_image = {
+        **PULLED_IMAGE,
+        "repository": "ghcr.io/open-webui/open-webui",
+        "tags": ["v0.9.0"],
+    }
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image" and method == "pull":
+            params = kwargs.get("params", {})
+            assert params["repository"] == "ghcr.io/open-webui/open-webui"
+            assert params["tag"] == "v0.9.0"
+            return {}
+        if api == "SYNO.Docker.Image" and method == "list":
+            return {"images": [found_image]}
+        return {}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_images(mcp, make_config(), client)
+
+    with patch("asyncio.sleep", new=AsyncMock()):
+        result = await tools["pull_image"]("ghcr.io/open-webui/open-webui:v0.9.0")
+
+    assert "Pulled ghcr.io/open-webui/open-webui:v0.9.0" in result
+
+
+@pytest.mark.asyncio
+async def test_pull_image_timeout():
+    from mcp_synology_container.modules.images import register_images
+
+    client = AsyncMock()
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image" and method == "pull":
+            return {}
+        # image never appears in list
+        return {"images": []}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_images(mcp, make_config(), client)
+
+    with patch("asyncio.sleep", new=AsyncMock()):
+        result = await tools["pull_image"]("nonexistent:latest")
+
+    assert "did not complete" in result
+    assert "120" in result
+
+
+@pytest.mark.asyncio
+async def test_pull_image_api_error():
+    from mcp_synology_container.dsm_client import SynologyError
+    from mcp_synology_container.modules.images import register_images
+
+    client = AsyncMock()
+    client.request.side_effect = SynologyError("pull failed", code=400)
+
+    mcp, tools = make_mock_mcp()
+    register_images(mcp, make_config(), client)
+
+    with patch("asyncio.sleep", new=AsyncMock()):
+        result = await tools["pull_image"]("bad/image:tag")
+
+    assert "Error" in result
+    assert "bad/image:tag" in result