feat: allocate IOL Docker application IDs from a pool disjoint from IOU

IOL interface MACs derive from the application ID (aabb.cc{app}{iface}),
so ids must be unique across opened projects sharing computes — the same
reason IOU has its allocator. IOL Docker nodes draw from the upper half
(512-1022, netiomux's fixed peer is 1023) so the two node types can
neither collide nor starve each other; IOU behavior is unchanged.

The controller sniffs the same GNS3_IOL_RUNNER environment marker the
compute uses to select IOLDockerVM (both the nested-properties and
template/top-level-kwarg shapes), stores the id in node properties like
IOU does, and passes it through the Docker create payload. Without an
allocation the compute falls back to a stable node-derived id in the
same upper range.

tests/controller/test_project.py

@@ -296,6 +296,47 @@ async def test_add_node_iou(controller):
     assert node3.properties["application_id"] == 3
 
 
+@pytest.mark.asyncio
+async def test_add_node_iol_docker(controller):
+    """
+    IOL Docker nodes (GNS3_IOL_RUNNER marker) get an application ID from the
+    upper half of the id space, disjoint from IOU's lower half
+    """
+
+    compute = MagicMock()
+    compute.id = "local"
+    project = await controller.add_project(project_id=str(uuid.uuid4()), name="test1")
+    project.emit_notification = MagicMock()
+
+    response = MagicMock()
+    compute.post = AsyncioMagicMock(return_value=response)
+
+    # template shape: environment as a top-level kwarg
+    node1 = await project.add_node(
+        compute, "iol1", None, node_type="docker", image="iol-xe/iol-xe:17-18-02", environment="GNS3_IOL_RUNNER=1"
+    )
+    # raw API shape: environment nested in properties
+    node2 = await project.add_node(
+        compute,
+        "iol2",
+        None,
+        node_type="docker",
+        properties={"image": "iol-xe/iol-xe:17-18-02", "environment": "GNS3_IOL_RUNNER=1"},
+    )
+    # plain docker nodes are left alone
+    node3 = await project.add_node(
+        compute, "web", None, node_type="docker", image="nginx", environment="FOO=1", adapters=1
+    )
+
+    assert node1.properties["application_id"] == 512
+    assert node2.properties["application_id"] == 513
+    assert "application_id" not in node3.properties
+
+    # IOU keeps its own pool: a subsequent IOU node still gets the lower half
+    node4 = await project.add_node(compute, "iou1", None, node_type="iou")
+    assert node4.properties["application_id"] == 1
+
+
 @pytest.mark.asyncio
 async def test_add_node_iou_with_multiple_projects(controller):
     """