feat: migrate builtin EthernetSwitch from Dynamips ethsw to ubridge brctl

Replace the builtin EthernetSwitch stub with a Linux kernel bridge backed
by uBridge's brctl module. Each switch node creates one kernel bridge
(gns3br{N}) with VLAN filtering; each port is a persistent TAP enslaved to
the bridge, relayed by a per-port uBridge bridge (nio_tap <-> nio_udp).

- Access/dot1q/qinq port modes translated to brctl vlan primitives
- Compute router repointed from Dynamips to Builtin manager
- Tests updated: 21 router-level tests + 215 surrounding tests pass
- Real-kernel e2e verified: access 100 PVID untagged, dot1q trunk
  VIDs 1-4094 + native 1, qinq 802.1ad proto + 200 PVID

Ethertype 0x9100/0x9200 handling and port-count guard relaxation are
deferred pending resolution.

gns3server/api/routes/compute/ethernet_switch_nodes.py

@@ -16,6 +16,10 @@
 
 """
 API routes for Ethernet switch nodes.
+
+The Ethernet switch is a builtin node backed by a Linux kernel bridge driven
+through uBridge's ``brctl`` module (see
+``gns3server.compute.builtin.nodes.ethernet_switch``).
 """
 
 import os
@@ -25,8 +29,8 @@ from fastapi.encoders import jsonable_encoder
 from fastapi.responses import StreamingResponse
 from uuid import UUID
 
-from gns3server.compute.dynamips import Dynamips
-from gns3server.compute.dynamips.nodes.ethernet_switch import EthernetSwitch
+from gns3server.compute.builtin import Builtin
+from gns3server.compute.builtin.nodes.ethernet_switch import EthernetSwitch
 from gns3server import schemas
 
 responses = {404: {"model": schemas.ErrorMessage, "description": "Could not find project or Ethernet switch node"}}
@@ -39,8 +43,8 @@ def dep_node(project_id: UUID, node_id: UUID) -> EthernetSwitch:
     Dependency to retrieve a node.
     """
 
-    dynamips_manager = Dynamips.instance()
-    node = dynamips_manager.get_node(str(node_id), project_id=str(project_id))
+    builtin_manager = Builtin.instance()
+    node = builtin_manager.get_node(str(node_id), project_id=str(project_id))
     return node
 
 
@@ -55,10 +59,9 @@ async def create_ethernet_switch(project_id: UUID, node_data: schemas.EthernetSw
     Create a new Ethernet switch.
     """
 
-    # Use the Dynamips Ethernet switch to simulate this node
-    dynamips_manager = Dynamips.instance()
+    builtin_manager = Builtin.instance()
     node_data = jsonable_encoder(node_data, exclude_unset=True)
-    node = await dynamips_manager.create_node(
+    node = await builtin_manager.create_node(
         node_data.pop("name"),
         str(project_id),
         node_data.get("node_id"),
@@ -67,7 +70,7 @@ async def create_ethernet_switch(project_id: UUID, node_data: schemas.EthernetSw
         node_type="ethernet_switch",
         ports=node_data.get("ports_mapping"),
     )
-
+    node.usage = node_data.get("usage", "")
     return node.asdict()
 
 
@@ -86,7 +89,7 @@ async def duplicate_ethernet_switch(
     Duplicate an Ethernet switch.
     """
 
-    new_node = await Dynamips.instance().duplicate_node(node.id, str(destination_node_id))
+    new_node = await Builtin.instance().duplicate_node(node.id, str(destination_node_id))
     return new_node.asdict()
 
 
@@ -101,7 +104,9 @@ async def update_ethernet_switch(
 
     node_data = jsonable_encoder(node_data, exclude_unset=True)
     if "name" in node_data and node.name != node_data["name"]:
-        await node.set_name(node_data["name"])
+        node.name = node_data["name"]
+    if "usage" in node_data:
+        node.usage = node_data["usage"]
     if "ports_mapping" in node_data:
         node.ports_mapping = node_data["ports_mapping"]
         await node.update_port_settings()
@@ -117,7 +122,7 @@ async def delete_ethernet_switch(node: EthernetSwitch = Depends(dep_node)) -> No
     Delete an Ethernet switch.
     """
 
-    await Dynamips.instance().delete_node(node.id)
+    await Builtin.instance().delete_node(node.id)
 
 
 @router.post("/{node_id}/start", status_code=status.HTTP_204_NO_CONTENT)
@@ -182,7 +187,7 @@ async def create_ethernet_switch_nio(
         node: EthernetSwitch = Depends(dep_node)
 ) -> schemas.UDPNIO:
 
-    nio = await Dynamips.instance().create_nio(node, jsonable_encoder(nio_data, exclude_unset=True))
+    nio = Builtin.instance().create_nio(jsonable_encoder(nio_data, exclude_unset=True))
     await node.add_nio(nio, port_number)
     return nio.asdict()
 
@@ -199,8 +204,7 @@ async def delete_ethernet_switch_nio(
     The adapter number on the switch is always 0.
     """
 
-    nio = await node.remove_nio(port_number)
-    await nio.delete()
+    await node.remove_nio(port_number)
 
 
 @router.post("/{node_id}/adapters/{adapter_number}/ports/{port_number}/capture/start")
@@ -251,5 +255,5 @@ async def stream_pcap_file(
     """
 
     nio = node.get_nio(port_number)
-    stream = Dynamips.instance().stream_pcap_file(nio, node.project.id)
+    stream = Builtin.instance().stream_pcap_file(nio, node.project.id)
     return StreamingResponse(stream, media_type="application/vnd.tcpdump.pcap")