feat(Data/neo4jDatabases): add Neo4j resource type and Kubernetes recipe

Data/neo4jDatabases/README.md

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+# Radius.Data/neo4jDatabases
+
+## Overview
+
+The `Radius.Data/neo4jDatabases` Resource Type represents a Neo4j graph database. It is intended for application-centric usage and can also be provisioned as a shared resource in a Radius Environment.
+
+## Recipes
+
+| Platform   | IaC       | Recipe Name                         | Stage |
+|------------|-----------|--------------------------------------|-------|
+| Kubernetes | Bicep     | `kubernetes-neo4j.bicep`             | Alpha |
+
+## Recipe Input Properties
+
+This Resource Type is in Alpha and does not expose developer-set input properties for the Recipe at this time. In future iterations, additional properties (for example, size and Neo4j-specific configuration) may be introduced.
+
+## Recipe Output Properties
+
+Recipes must populate the following read-only properties on the resource:
+
+- `host` (string): DNS hostname clients use to connect.
+- `port` (integer): Bolt port (typically `7687`).
+- `username` (string): Username for client connections.
+- `password` (string): Password for client connections.
+
+## Notes
+
+- The reference Kubernetes recipe is designed for development and evaluation. For production use, consider adding persistence (PVC), authentication, and backup/restore to your own recipe variant.

Data/neo4jDatabases/neo4jDatabases.yaml

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+namespace: Radius.Data
+types:
+  neo4jDatabases:
+    description: |
+      The Radius.Data/neo4jDatabases Resource Type deploys a Neo4j graph database. To create a new Neo4j database, define an Application and Container resource in your application definition Bicep file.
+
+        extension radius
+        param environment string
+
+        resource myapplication 'Radius.Core/applications@2025-08-01-preview' = { ... }
+        resource myContainer 'Radius.Compute/containers@2025-08-01-preview' = { ... }
+
+      Then add a `neo4jDatabases` resource.
+
+        resource neo4j 'Radius.Data/neo4jDatabases@2025-09-11-preview' = {
+          name: 'neo4j'
+          properties: {
+            application: myapplication.id
+            environment: environment
+          }
+        }
+
+      To connect to the new Neo4j database, add a connection between the container and the new Neo4j database. The final Container resource should look similar to:
+
+        resource myContainer 'Radius.Compute/containers@2025-08-01-preview' = {
+          name: 'myContainer'
+          properties: {
+            environment: environment
+            application: myapplication.id
+            containers: { ... }
+            connections: {
+              neo4jDb: {
+                source: neo4j.id
+              }
+            }
+          }
+        }
+
+      Within your container, your application code can obtain the host, port, username, and password values via environment variables automatically created. 
+
+        CONNECTION_NEO4JDB_HOST
+        CONNECTION_NEO4JDB_PORT
+        CONNECTION_NEO4JDB_DATABASE
+        CONNECTION_NEO4JDB_USERNAME
+        CONNECTION_NEO4JDB_PASSWORD
+
+    apiVersions:
+      '2025-09-11-preview':
+        schema:
+          type: object
+          properties:
+            environment:
+              type: string
+              description: (Required) The Radius Environment ID. Typically provided by the rad CLI. The typical value is `environment`.
+            application:
+              type: string
+              description: (Optional) The Radius Application ID when the database is app-scoped. Omit to provision a shared database in an Environment.
+            host:
+              type: string
+              readOnly: true
+              description: (Read-only) The DNS hostname used by clients to connect to Neo4j.
+            port:
+              type: integer
+              readOnly: true
+              description: (Read-only) The Bolt protocol port used to connect to Neo4j (typically `7687`).
+            username:
+              type: string
+              readOnly: true
+              description: (Read-only) The username for connecting to Neo4j.
+            password:
+              type: string
+              readOnly: true
+              description: (Read-only) The password for connecting to Neo4j.
+          required:
+            - environment

Data/neo4jDatabases/recipes/kubernetes/README.md

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+# Kubernetes Recipe - Neo4j (Alpha)
+
+This Alpha recipe deploys Neo4j to Kubernetes as an `apps/StatefulSet` with a `ReadWriteOnce` PersistentVolumeClaim and a `ClusterIP` Service exposing the Bolt port (7687). It is suitable for local development and evaluation.
+
+Authentication is enabled via parameters. The recipe accepts a username and password and returns these in the outputs so that the corresponding resource properties can be populated in Radius.
+
+Outputs:
+
+- `values.host`: Internal DNS name of the Service
+- `values.port`: Bolt port (7687)
+- `values.username`: Username provided to the recipe
+- `values.database`: Database name used by the deployment
+- `secrets.password`: Password provided to the recipe
+
+## Usage
+
+This recipe is intended to be registered to a Radius Environment and mapped to `Radius.Data/neo4jDatabases@2025-09-11-preview`.
+
+When a developer defines a `neo4jDatabases` resource, Radius will invoke this recipe and populate the resource outputs.
+
+### Parameters
+
+- `database` (string, default: resource name): Database name to configure.
+- `user` (string, default: `neo4j`): Username to provision.
+- `password` (secure string, default: `uniqueString(context.resource.id)`): Password to provision.
+- `tag` (string, default: `community`): Tag for the `neo4j` container image.
+
+### Notes
+
+- This reference recipe enables persistence via a 10Gi PVC and uses a single replica StatefulSet.
+- For production use, consider customizing storage class, resource requests/limits, authentication hardening, backup/restore, and service exposure.

Data/neo4jDatabases/recipes/kubernetes/bicep/kubernetes-neo4j.bicep

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+@description('Information about what resource is calling this Recipe. Generated by Radius.')
+param context object
+
+@description('Name of the Neo4j database. Defaults to the name of the Radius resource.')
+param database string = context.resource.name
+
+@description('Neo4j username')
+param user string = 'neo4j'
+
+@description('Neo4j password')
+@secure()
+#disable-next-line secure-parameter-default
+param password string = uniqueString(context.resource.id)
+
+@description('Tag to pull for the neo4j container image.')
+param tag string = 'community'
+
+extension kubernetes with {
+  kubeConfig: ''
+  namespace: context.runtime.kubernetes.namespace
+} as kubernetes
+
+var uniqueName = 'neo4j-${uniqueString(context.resource.id)}'
+var port = 7687
+
+resource svc 'core/Service@v1' = {
+  metadata: {
+    name: uniqueName
+    labels: {
+      name: uniqueName
+    }
+  }
+  spec: {
+    type: 'ClusterIP'
+    selector: {
+      app: 'neo4j'
+      resource: context.resource.name
+    }
+    ports: [
+      {
+        port: port
+      }
+    ]
+  }
+}
+
+resource neo4j 'apps/StatefulSet@v1' = {
+  metadata: {
+    name: uniqueName
+  }
+  spec: {
+    serviceName: uniqueName
+    replicas: 1
+    selector: {
+      matchLabels: {
+        app: 'neo4j'
+        resource: context.resource.name
+      }
+    }
+    template: {
+      metadata: {
+        labels: {
+          app: 'neo4j'
+          resource: context.resource.name
+          // Label pods with the application name so `rad run` can find the logs.
+          'radapp.io/application': context.application == null ? '' : context.application.name
+        }
+      }
+      spec: {
+        containers: [
+          {
+            name: 'neo4j'
+            image: 'neo4j:${tag}'
+            ports: [
+              {
+                containerPort: 7474
+                name: 'http'
+              }
+              {
+                containerPort: port
+                name: 'bolt'
+              }
+            ]
+            volumeMounts: [
+              {
+                name: 'neo4j-data'
+                mountPath: '/data'
+              }
+            ]
+          }
+        ]
+      }
+    }
+    volumeClaimTemplates: [
+      {
+        metadata: {
+          name: 'neo4j-data'
+        }
+        spec: {
+          accessModes: ['ReadWriteOnce']
+          resources: {
+            requests: {
+              storage: '10Gi'
+            }
+          }
+        }
+      }
+    ]
+  }
+}
+
+output result object = {
+  resources: [
+    '/planes/kubernetes/local/namespaces/${svc.metadata.namespace}/providers/core/Service/${svc.metadata.name}'
+    '/planes/kubernetes/local/namespaces/${neo4j.metadata.namespace}/providers/apps/Deployment/${neo4j.metadata.name}'
+  ]
+  values: {
+    host: '${svc.metadata.name}.${svc.metadata.namespace}.svc.cluster.local'
+    port: port
+    database: database
+    username: user
+  }
+  secrets: {
+    #disable-next-line outputs-should-not-contain-secrets
+    password: password
+  }
+}