feat: container liveness sync + node-runner slim base

- Add syncStatus() to InstanceService: detects crashed/stopped containers,
  marks them ERROR with last log line as context
- Reconcile now syncs container status first (detect dead before counting)
- Add 30s periodic sync loop in main.ts
- Switch node-runner from alpine to slim (Debian) for npm compatibility
  (fixes home-assistant-mcp-server binary not found on Alpine)

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

deploy/Dockerfile.node-runner

@@ -1,7 +1,8 @@
 # Base container for npm-based MCP servers (STDIO transport).
 # mcpd uses this image to run `npx -y <packageName>` when a server
 # has packageName but no dockerImage.
-FROM node:20-alpine
+# Using slim (Debian) instead of alpine for better npm package compatibility.
+FROM node:20-slim
 
 WORKDIR /mcp