Resolve primitive and literal rollout blockers

[swernerx]

Summary

• resolve the four named unsupported primitive/literal observations as stable regression limitations with explicit owners and implementation actions
• classify all three recovery-file OXC mapping gaps with stable, actionable ownership
• add a CI-enforced 100% all-selection accounting denominator so supported compatibility cannot hide classified selections
• keep unexplained semantic, transport, and mapping differences blocking
• update ADR-0020, the migration contract, fixture documentation, and checked rollout evidence

Boundary

Go remains the semantic authority and production fallback. Rust remains shadow-only. This does not switch authority, change the TS7 producer protocol or external consumers, or modify Palamedes.

Validation

• cargo fmt --manifest-path internal/oxc_reference/Cargo.toml --all -- --check
• cargo clippy --locked --manifest-path internal/oxc_reference/Cargo.toml --all-targets -- -D warnings
• cargo test --locked --manifest-path internal/oxc_reference/Cargo.toml
• GOCACHE=<repo-local> go test ./internal/semanticfacts ./internal/tsfacts ./cmd/tsfacts
• ./internal/oxc_reference/run-conformance.sh (28/28 accounted, 29/29 supported records, 0 unexplained differences)
• ./internal/oxc_reference/run-rollout.sh --output docs/evidence/primitive-literal-rollout-2026-08-17.json (two byte-identical complete runs, passes: true)
• npx dprint check
• npx hereby build

The complete local go test ./... passed all packages except macOS FSEvents-backed watcher tests, which cannot start FSEvents streams inside the sandbox. The focused changed-area suites above passed; PR CI runs the supported Linux matrix.

Closes #52