Track removal of residual OSTW owner-style evidence after deltin-rs migration

[Teakowa]

Goal

Remove the residual owner-style OSTW reference infrastructure from Wright after wrightkit/deltin-rs#49 establishes the authoritative DEL/OSTW evidence boundary.

Context

Wright's compatibility cleanup removes duplicated OPY oracle ownership immediately because opy-rs already owns and carries the corresponding live oracle/corpus infrastructure. OSTW is not yet in the same state: compatibility/ostw/ still contains the only complete pinned v3.4.0 reference metadata, explicit-root corpus/probes, recorded results, reconstruction evidence, and legacy runner.

Deleting that tree before deltin-rs#49 lands would create an evidence gap. Keeping it indefinitely would preserve the wrong repository ownership.

Scope

• Depend on and review the owner-side result of wrightkit/deltin-rs#49.
• Classify each remaining compatibility/ostw/ artifact as either:
  • authoritative language/reference evidence now owned by deltin-rs and removable from Wright; or
  • an immutable Wright consumer/integration snapshot concretely required by a current Wright test.
• Remove the owner-style acquisition/reproduction harness and any duplicated corpus/results no longer required by Wright.
• Repoint Wright OSTW/provider regression tests to the minimum retained recorded evidence or owner contract.
• Update Wright compatibility/provenance documentation after the final ownership cutover.

Non-goals

• Reimplementing DEL/OSTW semantics in Wright.
• Running the live OSTW compiler in default Wright CI.
• Removing regression evidence that is still required by an active Wright integration path without a replacement.

Acceptance criteria

• compatibility/ostw/ no longer acts as the authoritative DEL/OSTW oracle/corpus owner.
• Wright retains only evidence that a named Wright integration/product test actually consumes.
• No Wright test depends on live upstream OSTW/.NET execution.
• All retained snapshots have explicit owner/reference identity and provenance.
• Wright docs point to deltin-rs for authoritative DEL/OSTW compatibility evidence.

Dependency

• wrightkit/deltin-rs#49