After upgrade kexec into v1.13.2, CM5 eMMC takes ~2m13s between the SDHCI
controller registering and mmc0 actually becoming usable. The Talos config
acquire state machine (`acquire.go::stateDisk`) checks STATE in the first
seconds of boot, sees `VolumePhaseMissing`, and transitions one-way to
`stateEmbedded` -> `stateMaintenanceEnter`. When STATE later becomes
ready, the state machine doesn't re-enter `stateDisk`, so the node stays
in maintenance forever despite the on-disk config.yaml being intact.
This patch makes stateDisk tolerate transient phase=missing for up to
5 minutes (stateMissingDiskTimeout) before falling through to embedded.
A 5-second ticker on the outer Run loop ensures the timeout can fire
even when no further volume-status events arrive (e.g. truly missing
STATE on a fresh install).
Validated 2026-05-25 via canonical 3-CP rolling upgrade on a freshly
flashed v1.12.4 home-test cluster: all 3 blades upgraded sequentially
to v1.13.2-7 (this patch), each came back stage=running with config
loaded automatically and k8s Ready within ~5 min, no manual remediation.
See doc-compute-blade-kubernetes/talos-upgrade-validation/session-2026-05-25/E2E-VALIDATED.md.
Fast-init hardware sees no change — STATE reaches ready within seconds
and the existing path runs.
