Storage and backup status page

[LiukScot]

Summary

New /storage page showing Docker volume disk usage, per-container storage, filesystem mount points, and backup status.

Problem

No visibility into what's consuming disk space across Docker volumes and containers. No way to check if backups are running.

Implementation

Backend

• New internal/collectors/storage.go:
  • Query Docker API for volume list + sizes (/system/df)
  • Parse container mounts to show per-container storage paths
  • Read filesystem mount points via /proc/mounts with statfs for each
  • Scan for common backup tools (check cron jobs, systemd timers, look for backup scripts in common locations)
• API endpoints:
  • GET /api/v1/storage/volumes — Docker volumes with sizes
  • GET /api/v1/storage/mounts — filesystem mount points with usage
  • GET /api/v1/storage/backups — detected backup schedules and last run times

Frontend

• Horizontal bar charts for volume sizes (sorted largest first)
• Mount point cards with usage progress bars and color coding (green < 70%, yellow < 85%, red >= 85%)
• Backup status cards: last run time, next scheduled, success/failure indicator

Files to create/modify

• New internal/collectors/storage.go
• internal/collectors/docker.go — extend with system df query
• internal/server/server.go — new routes
• New frontend/src/routes/storage/+page.svelte
• frontend/src/routes/+layout.svelte — add nav item