Enhance DurableStateStore TCK with OCC, serialization, and soft-delete tests

[drse]

Summary

Enhances the AI-drafted DurableStateStore TCK from #2833 to address the gaps
discussed in #2831 — specifically optimistic-concurrency checks, serialization
roundtrip, and the deprecated soft-delete overload.

This PR supersedes #2833. The first three commits are @pjfanning's original
work cherry-picked unchanged; the fourth commit layers the enhancements on top.

Changes

Capability flags (CapabilityFlags.scala)

DurableStateStoreCapabilityFlags extended with three new flags:

• supportsUpsertWithRevisionCheck — when on, asserts that an upsert with
  a stale revision is rejected and the prior state is preserved.
• supportsSerialization — when on, asserts that values roundtrip through
  the configured Pekko serializer using the same TestPayload(probe.ref)
  pattern as JournalSpec. Defaults to on in DurableStateStoreSpec to
  match the JournalSpec convention; the in-memory testkit reference TCK
  explicitly overrides to off since the testkit holds raw refs.
• supportsSoftDelete — when on, asserts the deprecated single-argument
  deleteObject(persistenceId) overload deletes regardless of revision.

Spec additions (DurableStateStoreSpec.scala)

• New required test: "upsert again after a deletion" — ensures the store
  accepts a fresh upsert at a higher revision after a delete.
• New optional tests behind each new capability flag.
• New preparePersistenceId(pid: String) hook called from beforeEach,
  mirroring JournalSpec. Plugins backed by external state (JDBC, NATS, etc.)
  can override this to clean residual records between tests.
• Test timeout promoted to protected so subclasses can override for slow
  stores.

Reference TCK (PersistenceTestKitDurableStateStoreTCKSpec.scala)

Added an explicit supportsSerialization = off override since the in-memory
testkit doesn't serialize values.

Docs (persistence-journals.md + doc-test files)

Added a brief subsection in the ## Plugin TCK section mirroring the
Journal/Snapshot pattern, with #durable-state-tck-scala and
#durable-state-tck-java snippet markers.

Deferred for follow-up

These ideas surfaced during this work but were deliberately scoped out:

• Query-by-tag roundtrip — verify a tag passed to upsertObject is
  retrievable via DurableStateStoreQuery.changes(...). Requires extending the
  TCK to cover the read-side query SPI.
• Get-after-delete revision contract — current tests assert value=None
  after delete but not what revision should be (impls differ; needs a
  committer decision).
• Idempotent upsert — repeating upsertObject(pid, N, sameValue, tag) for
  replay safety.
• Slice-based query roundtrip (DurableStateStoreBySliceQuery).
• Paged persistence-ID enumeration (DurableStateStorePagedPersistenceIdsQuery).

Happy to open follow-up PRs once this lands.

Test plan

• sbt scalafmtCheckAll — clean
• sbt persistence-tck/Test/compile docs/Test/compile — clean
• sbt "persistence-testkit/Test/testOnly *PersistenceTestKitDurableStateStoreTCKSpec" —
  6/6 required tests pass; 4 optional skip as expected (testkit doesn't enforce
  OCC, doesn't serialize, has a no-op deleteObject(pid)).

Closes #2831.

[He-Pin]

Not 2023?

[pjfanning]

it is copied from a file that has 2022 in it

[He-Pin]

but IIRC akka will update the year every year

[pjfanning]

we shouldn't update the date if we don't grab newer akka code from 2023 - this PR does not grab any 2023 akka code

[He-Pin]

lgtm

[pjfanning]

Merged, thanks