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/README.md

@@ -14,8 +14,12 @@ This Helm chart deploys the Nextcloud MCP (Model Context Protocol) Server on a K
 ### Quick Start with Basic Authentication
 
 ```bash
+# Add the Helm repository
+helm repo add nextcloud-mcp https://cbcoutinho.github.io/nextcloud-mcp-server
+helm repo update
+
 # Install with basic auth (recommended for most users)
-helm install nextcloud-mcp ./helm/nextcloud-mcp-server \
+helm install nextcloud-mcp nextcloud-mcp/nextcloud-mcp-server \
   --set nextcloud.host=https://cloud.example.com \
   --set auth.basic.username=myuser \
   --set auth.basic.password=mypassword
@@ -47,7 +51,7 @@ resources:
 Install with your custom values:
 
 ```bash
-helm install nextcloud-mcp ./helm/nextcloud-mcp-server -f custom-values.yaml
+helm install nextcloud-mcp nextcloud-mcp/nextcloud-mcp-server -f custom-values.yaml
 ```
 
 ### OAuth Authentication Mode (Experimental)
@@ -529,13 +533,17 @@ openai:
 ### To upgrade an existing deployment:
 
 ```bash
-helm upgrade nextcloud-mcp ./helm/nextcloud-mcp-server -f custom-values.yaml
+# Update the repository
+helm repo update
+
+# Upgrade with your custom values
+helm upgrade nextcloud-mcp nextcloud-mcp/nextcloud-mcp-server -f custom-values.yaml
 ```
 
 ### To upgrade with new values:
 
 ```bash
-helm upgrade nextcloud-mcp ./helm/nextcloud-mcp-server \
+helm upgrade nextcloud-mcp nextcloud-mcp/nextcloud-mcp-server \
   --set resources.limits.memory=1Gi
 ```