feat(resume): durable local_root + resume the scan instead of restarting it

[nghiemv]

A pod OOMKill discarded the whole run: local_root was Path("Local") on the
ephemeral overlay, so the catalog, the flushed storm-stats.csv scan progress, and
the DSS grids died with the pod. The .checkpoint skip-list also skipped
process-storms on resume, leaving ctx["collection"] unset and crashing downstream.

Changes:

• local_root honors CC_LOCAL_ROOT (point at the /model PVC); unset keeps the
  Local default.
• process-storms resume ladder: reload complete catalog → resume_collection over
  only missing dates → fresh search. A mid-scan OOM resumes where it died.
• Remove the .checkpoint skip-list. Actions are idempotent against local_root, so
  a resumed run re-runs from the top; process-storms always runs, so
  ctx["collection"] is always repopulated.

Deploy pairing (required on-cluster): set CC_LOCAL_ROOT to the durable /model
PVC and add an Argo retryStrategy. The mount must be block, not object-FUSE —
multi_processor fsyncs the CSV per date.

Happy path unchanged; resume adds seconds to save hours. New
test/test_process_storms_resume.py covers the partial-scan detector.

[nghiemv]

Closing -- might prefer fail-fast instead of resume

[nghiemv]

Closing — declining in favor of the performance direction.

Stateful resume is a bridge for when the scan is long and failure-prone. That premise no longer holds once the shippable defaults land:

• rolling-window scan (perf(process-storms): rolling-window AORC scan, read each year once (~3-5x, opt-out) #16) makes the scan ~3–12× faster (read each AORC year once),
• AORC pre-flight (feat(process-storms): fail-fast AORC pre-flight before the scan #15) fails fast on missing years before any expensive work,
• cgroup worker sizing (fix(convert-to-dss): size worker pool from cgroup budget, not host CPUs #13, merged) prevents the OOM that motivated this.

With the scan fast, fail-fast, and OOM-safe, re-running from scratch is cheap — so the resume machinery here (durable checkpoint, param-fingerprint, quarantine, CSV repair) is complexity that isn't warranted. Superseded, not lost: reopen if a future long/monolithic stage brings the premise back.