Summary

Fix storage headline totals when Sonarr and Radarr expose multiple root-folder paths that all point at the same underlying filesystem.

This update now:

• prefers root-folder-backed mounts when computing the headline total
• keys root-folder selection by instanceType + instanceId so Sonarr and Radarr IDs do not collide
• keeps the Arr root-folder merge logic shared in ServarrApi
• dedupes accurate mounts per host using the best available filesystem-like signature:
  • label + totalSpace when a stable volume label is present
  • otherwise totalSpace + MiB-bucketed freeSpace to absorb tiny cross-instance drift without collapsing obviously different same-size disks

Closes #2720.

Root Cause

getDiskspaceWithRootFolders() can return multiple distinct paths like /movies, /tv, and /downloads for the same shared filesystem.

Before this change, computeTotals() deduped by normalized path, so those entries were summed independently even when they referred to the same media disk.

Notes

Arr APIs do not expose a stable filesystem or device identifier in these payloads, so the totals logic still has to rely on a heuristic.

For accurate mounts without a label, the fallback now uses totalSpace + MiB-bucketed freeSpace as the filesystem signature. That fixes the shared-filesystem double-count while avoiding the stricter totalSpace-only collision on equal-capacity disks with materially different usage. Two separate unlabeled filesystems on the same host could still theoretically collide if they expose the same total space and land in the same free-space bucket.

Validation

• Added focused unit coverage for:
  • shared-filesystem root folders being counted once
  • overlapping radarr(1) / sonarr(1) IDs not colliding
  • same-host free-space drift still merging shared filesystems
  • same-host equal-capacity disks with different usage staying distinct
  • inaccurate-total path dedupe
  • getRootFolders() returning undefined in the shared Servarr helper
• Ran:
  • yarn workspace @maintainerr/server test --runInBand src/modules/storage-metrics/storage-metrics.service.spec.ts src/modules/api/servarr-api/common/servarr-api.service.spec.ts
  • yarn workspace @maintainerr/server tsc --noEmit
  • yarn workspace @maintainerr/server build
• Result: all passed