Local disks not mounted for `web` service sandboxes

Summary

Apps that define [[services.web.disks]] with provider = "local" in their app.toml do not get the disk mounted in their sandbox. The sandbox is also scheduled as stateful=false despite having a disk definition. This causes apps like uptime-kuma to crash because their data directory doesn't exist.

Affected apps on Garden

• uptime-kuma — crashes with ENOENT: no such file or directory, mkdir './data/' because /miren/data/local (the disk mount path) doesn't exist in the container
• victoriametrics — "crashed" status is a cascade from failing to scrape uptime-kuma; victoriametrics itself runs fine
• socials — also crashed, may be same issue (not investigated)

Observations

• Disks defined on non-web services work correctly. Tempo's [[services.tempo.disks]] mounts /miren/data/local as expected — confirmed via /proc/<pid>/mountinfo showing the ext4 bind mount from /dev/sdb.

• Disks defined on the web service do not mount. Tempo's web service (Caddy, no disk defined) correctly has no mount. But uptime-kuma's web service (disk defined) also has no mount — the disk definition is ignored.

• The sandbox scheduler treats web service sandboxes with disks as stateful=false:

  scheduling stateless sandbox to available node (no runners)
  

• A fresh miren deploy does not fix the issue — the new version's sandboxes also fail to mount the disk.

• miren app run also does not mount disks (may be expected/separate).

Reproduction

# app.toml — this disk config is ignored at runtime
[[services.web.disks]]
name = "data"
provider = "local"
mount_path = "/miren/data/local"

Deploy any app with the above config; the /miren/data/local path will not exist in the web service sandbox.

Expected behavior

provider = "local" disks on the web service should be mounted the same way they are for other service names. The sandbox should be scheduled as stateful=true when it has disk definitions.

Environment

• Cluster: Garden (miren-garden, us-central1-a, miren-development)
• Disk definitions added in PR #57