marker: fix PUT marker with an enabled-only body (bpf no longer required)

update_marker reused MarkerCreate, whose bpf is required, so a partial PUT like
{"enabled": false} was rejected with 422 "bpf field required". Add a MarkerUpdate
schema with every field optional (bpf included; capture_node_id and name are
create-only/path-driven and omitted) and use it for the PUT route — partial
updates now validate cleanly.

gns3server/api/routes/controller/links.py

@@ -497,7 +497,7 @@ async def delete_marker(
 )
 async def update_marker(
     marker_name: str,
-    marker_data: schemas.MarkerCreate,
+    marker_data: schemas.MarkerUpdate,
     link: Link = Depends(dep_link)
 ) -> dict:
     """

gns3server/schemas/__init__.py

@@ -20,7 +20,7 @@ from .common import ErrorMessage
 from .version import Version
 
 # Controller schemas
-from .controller.links import LinkCreate, LinkUpdate, Link, UDPPortInfo, EthernetPortInfo, LinkCapture, MarkerCreate, MarkerDefinitionCreate
+from .controller.links import LinkCreate, LinkUpdate, Link, UDPPortInfo, EthernetPortInfo, LinkCapture, MarkerCreate, MarkerUpdate, MarkerDefinitionCreate
 from .controller.computes import ComputeCreate, ComputeUpdate, ComputeVirtualBoxVM, ComputeVMwareVM, ComputeDockerImage, AutoIdlePC, Compute
 from .controller.templates import TemplateCreate, TemplateUpdate, TemplateUsage, Template
 from .controller.images import Image, ImageType

gns3server/schemas/controller/links.py

@@ -191,6 +191,29 @@ class MarkerCreate(BaseModel):
     )
 
 
+class MarkerUpdate(BaseModel):
+    """
+    Body for updating a marker — partial update, every field optional.
+
+    ``bpf`` is optional here (it is required on create). ``capture_node_id`` and
+    ``name`` are create-only / path-driven and intentionally absent; an explicit
+    ``direction: null`` clears the direction back to both (omitting keeps it).
+    """
+
+    bpf: Optional[str] = None
+    tag: Optional[int] = None
+    direction: Optional[str] = Field(
+        None,
+        pattern=r"^(tx|rx)$",
+        description="Direction filter; an explicit null clears it to both. Omit to keep.",
+    )
+    color: Optional[str] = Field(None, description="Hex color render hint, e.g. '#ff5722'")
+    highlight_duration: Optional[int] = Field(
+        None, ge=1, description="UI highlight duration in ms; null = UI default"
+    )
+    enabled: Optional[bool] = Field(None, description="Toggle the marker on/off (instant).")
+
+
 class MarkerDefinitionCreate(BaseModel):
     """
     Body for creating / updating a project-level marker definition.