feat(helm): add Qdrant local mode support with three deployment options [skip ci]

Add support for three Qdrant deployment modes in Helm chart:
1. In-memory mode (:memory:) - Default, zero-config, ephemeral storage
2. Persistent local mode (path-based) - File-based storage with PVC
3. Network mode (URL-based) - Dedicated Qdrant service or external instance

Changes:
- Restructured qdrant configuration in values.yaml with mode selector
- Added conditional environment variable logic in deployment.yaml
- Created PVC template for persistent local mode with optional existingClaim
- Added qdrantPvcName helper template in _helpers.tpl
- Updated README.md with Helm registry URL (https://cbcoutinho.github.io/nextcloud-mcp-server)

Breaking change: Default changed from requiring qdrant.enabled to using
in-memory mode (:memory:) when no Qdrant configuration is provided.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

charts/nextcloud-mcp-server/values.yaml

@@ -277,37 +277,76 @@ vectorSync:
   # Maximum queue size for documents pending indexing
   queueMaxSize: 10000
 
-# Qdrant Vector Database
-# Deployed as a subchart when enabled. All values are passed through to the qdrant/qdrant chart.
-# See https://github.com/qdrant/qdrant-helm for full configuration options.
+# Qdrant Vector Database Configuration
+# Three deployment modes available:
+# 1. Local In-Memory: Fast, ephemeral, zero-config (mode: "memory")
+# 2. Local Persistent: File-based, survives restarts (mode: "persistent")
+# 3. Network: Dedicated Qdrant service, production-ready (mode: "network")
 qdrant:
-  # Enable Qdrant subchart deployment
-  enabled: false
-  # Number of Qdrant replicas
-  replicaCount: 1
-  image:
-    # Qdrant version
-    tag: v1.12.5
-  # Optional API key for Qdrant authentication
-  apiKey: ""
-  config:
-    cluster:
-      # Enable distributed cluster mode
-      enabled: false
-  # Persistent storage for vector data
-  persistence:
-    size: 10Gi
+  # Qdrant mode: "memory", "persistent", or "network"
+  # - memory: In-memory storage (:memory:) - default, zero config, data lost on restart
+  # - persistent: Local file storage - data persists across restarts, suitable for small/medium deployments
+  # - network: Dedicated Qdrant service (see networkMode below)
+  mode: "memory"
+
+  # Collection name for vector data
+  collection: "nextcloud_content"
+
+  # Local persistent mode configuration (only used when mode: "persistent")
+  localPersistence:
+    # Enable persistent volume for local Qdrant data
+    enabled: true
+    # Storage class (leave empty for default)
     storageClass: ""
-    accessModes:
-      - ReadWriteOnce
-  # Resource limits and requests
-  resources:
-    requests:
-      cpu: 200m
-      memory: 512Mi
-    limits:
-      cpu: 1000m
-      memory: 2Gi
+    accessMode: ReadWriteOnce
+    # Size for local Qdrant storage
+    size: 1Gi
+    # Path where Qdrant data is stored (relative to /app/data)
+    # Default: /app/data/qdrant
+    dataPath: "/app/data/qdrant"
+    # Use existing PVC
+    existingClaim: ""
+
+  # Network mode configuration (only used when mode: "network")
+  networkMode:
+    # Deploy Qdrant as a subchart (if true) or use external Qdrant (if false)
+    deploySubchart: false
+    # External Qdrant URL (used when deploySubchart: false)
+    # Example: "http://qdrant.default.svc.cluster.local:6333"
+    externalUrl: ""
+    # Optional API key for Qdrant authentication
+    apiKey: ""
+    # Use existing secret for API key
+    existingSecret: ""
+    secretKey: "api-key"
+
+  # Qdrant subchart configuration (only used when mode: "network" and networkMode.deploySubchart: true)
+  # All values are passed through to the qdrant/qdrant chart.
+  # See https://github.com/qdrant/qdrant-helm for full configuration options.
+  subchart:
+    # Number of Qdrant replicas
+    replicaCount: 1
+    image:
+      # Qdrant version
+      tag: v1.12.5
+    config:
+      cluster:
+        # Enable distributed cluster mode
+        enabled: false
+    # Persistent storage for vector data
+    persistence:
+      size: 10Gi
+      storageClass: ""
+      accessModes:
+        - ReadWriteOnce
+    # Resource limits and requests
+    resources:
+      requests:
+        cpu: 200m
+        memory: 512Mi
+      limits:
+        cpu: 1000m
+        memory: 2Gi
 
 # Ollama Embedding Service
 # Deployed as a subchart when enabled. All values are passed through to the ollama/ollama chart.