feat: Add Infrahub Jinja2 transform for MLAG configuration (#22)

- Add GraphQL query mlag_intent.gql: queries InfraMlagPeerConfig by
  device name, returning local IP, peer address, heartbeat peer IP,
  MLAG domain (domain-id, virtual-mac, heartbeat VRF, dual-primary
  detection settings, peer/iBGP VLANs, peer devices), local interface
  SVI name, and peer-link LAG name
- Add Jinja2 template mlag_yang.j2: renders a JSON object targeting
  Arista-native YANG path /arista-mlag-augments:mlag/config; returns
  empty array [] for devices with no MLAG config (spines); all optional
  relationship accesses guarded with 'is defined and is not none' checks
- Update .infrahub.yml: register mlag_intent query and mlag_yang_transform
- Add unit test fixtures for leaf1 (full MLAG config) and spine1 (empty
  response → []) following jinja2-transform-unit-render format

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

infrahub/transforms/tests/mlag_yang/leaf1/input.json

@@ -0,0 +1,96 @@
+{
+  "data": {
+    "InfraMlagPeerConfig": {
+      "edges": [
+        {
+          "node": {
+            "local_interface_ip": {
+              "value": "10.0.199.254/31"
+            },
+            "peer_address": {
+              "value": "10.0.199.255"
+            },
+            "heartbeat_peer_ip": {
+              "value": "172.16.0.50"
+            },
+            "device": {
+              "node": {
+                "name": {
+                  "value": "leaf1"
+                }
+              }
+            },
+            "mlag_domain": {
+              "node": {
+                "domain_id": {
+                  "value": "leafs-1-2"
+                },
+                "virtual_mac": {
+                  "value": "c001.cafe.babe"
+                },
+                "heartbeat_vrf": {
+                  "value": "mgmt"
+                },
+                "dual_primary_detection": {
+                  "value": true
+                },
+                "dual_primary_delay": {
+                  "value": 10
+                },
+                "dual_primary_action": {
+                  "value": "errdisable"
+                },
+                "devices": {
+                  "edges": [
+                    {
+                      "node": {
+                        "name": {
+                          "value": "leaf1"
+                        }
+                      }
+                    },
+                    {
+                      "node": {
+                        "name": {
+                          "value": "leaf2"
+                        }
+                      }
+                    }
+                  ]
+                },
+                "peer_vlan": {
+                  "node": {
+                    "vlan_id": {
+                      "value": 4090
+                    }
+                  }
+                },
+                "ibgp_vlan": {
+                  "node": {
+                    "vlan_id": {
+                      "value": 4091
+                    }
+                  }
+                }
+              }
+            },
+            "local_interface": {
+              "node": {
+                "name": {
+                  "value": "Vlan4090"
+                }
+              }
+            },
+            "peer_link": {
+              "node": {
+                "name": {
+                  "value": "Port-Channel999"
+                }
+              }
+            }
+          }
+        }
+      ]
+    }
+  }
+}

infrahub/transforms/tests/mlag_yang/leaf1/output.json

@@ -0,0 +1,22 @@
+{
+  "mlag": {
+    "config": {
+      "domain-id": "leafs-1-2",
+      "peer-link": "Port-Channel999",
+      "local-interface": "Vlan4090",
+      "peer-address": "10.0.199.255",
+      "shutdown": false
+    },
+    "dual_primary_detection": {
+      "enabled": true,
+      "delay": 10,
+      "action": "errdisable",
+      "heartbeat_peer_ip": "172.16.0.50",
+      "heartbeat_vrf": "mgmt"
+    },
+    "virtual_mac": "c001.cafe.babe",
+    "peer_vlan_id": 4090,
+    "ibgp_vlan_id": 4091,
+    "local_interface_ip": "10.0.199.254/31"
+  }
+}

infrahub/transforms/tests/mlag_yang/spine1/input.json

@@ -0,0 +1,7 @@
+{
+  "data": {
+    "InfraMlagPeerConfig": {
+      "edges": []
+    }
+  }
+}

infrahub/transforms/tests/mlag_yang/spine1/output.json

@@ -0,0 +1 @@
+[]

infrahub/transforms/tests/mlag_yang/test.yml

@@ -0,0 +1,21 @@
+---
+version: "1.0"
+infrahub_tests:
+  - resource: Jinja2Transform
+    resource_name: mlag_yang_transform
+    tests:
+      - name: smoke_check
+        spec:
+          kind: jinja2-transform-smoke
+      - name: render_leaf1
+        spec:
+          kind: jinja2-transform-unit-render
+          directory: infrahub/transforms/tests/mlag_yang/leaf1
+          input: input.json
+          output: output.json
+      - name: render_spine1
+        spec:
+          kind: jinja2-transform-unit-render
+          directory: infrahub/transforms/tests/mlag_yang/spine1
+          input: input.json
+          output: output.json