feat: add GitHub MCP sidecar and fix Home Assistant MCP command (fixes #26)

- Fixed Home Assistant MCP command flags from --sse-server-host/port to --host/port
- Added GitHub MCP server as new sidecar (enabled by default)
- Uses existing GITHUB_TOKEN from environment
- Updated documentation and .mcp.json configuration

The GitHub MCP sidecar provides AI assistants with ability to interact with
GitHub repositories, issues, PRs, and more using the same token used for
repository cloning.

Fixes #26

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

chart/values.yaml

@@ -108,3 +108,16 @@ mcpSidecars:
       limits:
         memory: "256Mi"
         cpu: "500m"
+  github:
+    enabled: true  # Enabled by default, uses GITHUB_TOKEN from env
+    image:
+      repository: ghcr.io/modelcontextprotocol/servers/github
+      tag: latest  # Update to specific version once available
+    port: 8088
+    resources:
+      requests:
+        memory: "64Mi"
+        cpu: "50m"
+      limits:
+        memory: "256Mi"
+        cpu: "500m"