Fix Garage healthcheck: use garage CLI instead of wget

The Garage container doesn't have wget. Use the built-in garage CLI
with 'stats -a' command to check if the node is healthy.

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

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

templates/compose/garage.yaml

@@ -53,7 +53,7 @@ services:
           admin_token_file = "env:GARAGE_ADMIN_TOKEN"
           metrics_token_file = "env:GARAGE_METRICS_TOKEN"
     healthcheck:
-      test: ["CMD", "wget", "-q", "--spider", "http://127.0.0.1:3903/health"]
+      test: ["CMD", "/garage", "stats", "-a"]
       interval: 10s
       timeout: 5s
       retries: 5