Provider-neutral projection conformance checkpoint (2026-09-12)

Moved without content change from typescript-control-plane-migration-v0.md (former section "Provider-neutral projection conformance checkpoint (2026-09-12)") on 2026-09-26; RFC baseline 3e443ad7c. Checkpoint records live in this ledger, not in the RFC body.

The conformance boundary now has one projection-fixture builder for both the legacy v0 and native Todo record shapes. It owns deterministic Unicode ordering, read-model digest/field construction, and the compatibility-only conversion; provider tests no longer hand-rebuild those fields. The scale envelope declares status ordering explicitly and validates its counts, so changing JSON key order cannot silently change which Todo receives a lease, successor, or archive role.

The File, SQLite, and NoKV suites now execute the same production-scale terminal cases in both record shapes. A separate parity harness replays one seed, observation, and lease sequence through all three isolated providers and compares the logical head plus committed event/projection/receipt trace while ignoring provider-specific revision tokens. This is conformance evidence, not a new authority writer, provider default, or promotion claim; PostgreSQL remains under its existing real-service qualification gate.

The old v0 consumer manifest remains readable and retains all existing fields. Default Markdown capture still emits v0; this PR neither rewrites stored heads nor auto-promotes a goal. The schema split is not permission to drop v0 provenance or change legacy ordering during a later migration.