feat: Add Infrahub Jinja2 transform for VRF/L3VNI configuration (#21)

- Add GraphQL query vrf_intent.gql: queries InfraVRFDeviceAssignment by
  device name, returning device-specific RD, VRF attributes (name,
  description, l3vni), and both device-level and VRF-level import/export
  route targets for fallback logic
- Add Jinja2 template vrf_yang.j2: renders a JSON array of VRF config
  objects with RD fallback (device → VRF-level) and RT merge logic
  (device-level if present, otherwise VRF-level); all optional
  relationships guarded with 'is defined and is not none' checks
- Update .infrahub.yml: register vrf_intent query and vrf_yang_transform
- Add unit test fixtures for leaf3: input.json (mock GraphQL response)
  and output.json (expected rendered JSON array)

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

infrahub/transforms/tests/vrf_yang/input.json

@@ -0,0 +1,82 @@
+{
+  "data": {
+    "InfraVRFDeviceAssignment": {
+      "edges": [
+        {
+          "node": {
+            "route_distinguisher": {
+              "value": "10.0.250.13:1"
+            },
+            "vrf": {
+              "node": {
+                "name": {
+                  "value": "gold"
+                },
+                "description": {
+                  "value": "VRF gold - L3 VXLAN with symmetric IRB"
+                },
+                "route_distinguisher": {
+                  "value": null
+                },
+                "l3vni": {
+                  "node": {
+                    "vni": {
+                      "value": 100001
+                    },
+                    "vni_type": {
+                      "value": "l3vni"
+                    }
+                  }
+                },
+                "import_targets": {
+                  "edges": [
+                    {
+                      "node": {
+                        "target": {
+                          "value": "1:100001"
+                        }
+                      }
+                    }
+                  ]
+                },
+                "export_targets": {
+                  "edges": [
+                    {
+                      "node": {
+                        "target": {
+                          "value": "1:100001"
+                        }
+                      }
+                    }
+                  ]
+                }
+              }
+            },
+            "import_targets": {
+              "edges": [
+                {
+                  "node": {
+                    "target": {
+                      "value": "1:100001"
+                    }
+                  }
+                }
+              ]
+            },
+            "export_targets": {
+              "edges": [
+                {
+                  "node": {
+                    "target": {
+                      "value": "1:100001"
+                    }
+                  }
+                }
+              ]
+            }
+          }
+        }
+      ]
+    }
+  }
+}

infrahub/transforms/tests/vrf_yang/output.json

@@ -0,0 +1,15 @@
+[
+  {
+    "description": "VRF gold - L3 VXLAN with symmetric IRB",
+    "export_targets": [
+      "1:100001"
+    ],
+    "import_targets": [
+      "1:100001"
+    ],
+    "l3vni": 100001,
+    "redistribute_connected": true,
+    "route_distinguisher": "10.0.250.13:1",
+    "vrf_name": "gold"
+  }
+]

infrahub/transforms/tests/vrf_yang/test.yml

@@ -0,0 +1,15 @@
+---
+version: "1.0"
+infrahub_tests:
+  - resource: Jinja2Transform
+    resource_name: vrf_yang_transform
+    tests:
+      - name: smoke_check
+        spec:
+          kind: jinja2-transform-smoke
+      - name: render_leaf3
+        spec:
+          kind: jinja2-transform-unit-render
+          directory: infrahub/transforms/tests/vrf_yang
+          input: input.json
+          output: output.json