feat: bump dependencies and add kubectl, k9s, Flux CLI

Update pinned versions: Node.js 22→24 LTS, Helm 3.17→4.1, Go 1.23→1.26.
Add kubectl, k9s, and Flux CLI to the container image.
Update MCP sidecars: kubernetes v0.0.59, flux-operator v0.45.0,
mcp-helm v1.3.3, homeassistant 7.1.0.
Bump chart version to 2.7.0.

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

chart/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 name: devcontainer
 description: Dev Container with AI coding agents and MCP sidecars
 type: application
-version: 2.6.0
+version: 2.7.0
 appVersion: "latest"
 keywords:
   - development