Redesign host row layout, fix Docker build, add S3 Singapore

- Host row: two-layer layout with name/URL on the left (normal flow)
  and latency/stats on the right (absolute positioned), preventing
  overlap and keeping sparklines aligned
- Docker: install git in build stage and include .git in context so
  vite can resolve commit hash for footer
- Add S3 ap-southeast-1 (Singapore) endpoint for AWS peering comparison

.dockerignore

@@ -1,6 +1,5 @@
 node_modules
 dist
-.git
 .DS_Store
 *.log
 .claude