Physical Provisioning

[smklein]

Add pessimistic physical provisioning accounting (RFD 639)

Track actual physical storage consumption (including replication overhead and ZFS reservations) separately from the existing virtual provisioning counters. This enables accurate capacity planning and quota enforcement based on real physical bytes consumed.

• New physical_provisioning_collection and physical_provisioning_resource tables with three counters: writable, zfs_snapshot, and read_only bytes
• CTE query builder with atomic deduplication of shared read-only resources (images/snapshots referenced by multiple disks)
• Physical byte calculation functions for distributed (3.75x) and local disks
• Saga integration: disk, snapshot, image, and instance lifecycles now atomically update physical provisioning alongside record creation/deletion
• Image promote/demote adjusts physical provisioning at the correct levels
• Optional physical_storage silo quota with API versioning (2026021100)
• Utilization views expose physical_disk_bytes_provisioned