A-META R2 unlocks: wire policy module + trajectory-audit feature stub

- Added pub mod policy gate behind auth-rls-lite (PolicyRewriter trait
  + ColumnMaskRewriter from epiphany E1)
- Added trajectory-audit feature alias on lance-graph-contract for the
  forward-stub step_trajectory_hash helper (E4 cross-PR bridge)

Author: claude

crates/lance-graph-callcenter/src/lib.rs

@@ -100,3 +100,10 @@ pub mod postgrest;
 //         A3: in-memory ring buffer skeleton; Lance-backed writer arrives later.
 #[cfg(feature = "audit-log")]
 pub mod audit;
+
+// PR #278 outlook E1 — generalized PolicyRewriter trait (column masking,
+// row encryption, differential privacy stubs) sharing the OptimizerRule slot
+// with the existing RLS rewriter. Gated on auth-rls-lite (where the
+// DataFusion types live).
+#[cfg(any(feature = "auth-rls-lite", feature = "auth-rls", feature = "auth", feature = "full"))]
+pub mod policy;

crates/lance-graph-contract/Cargo.toml

@@ -9,3 +9,9 @@ keywords = ["lance", "graph", "contract", "orchestration", "thinking"]
 [dependencies]
 # Zero dependencies by design — this is a trait-only crate.
 # Consumers depend on this; implementations depend on lance-graph-planner.
+
+[features]
+# A-unlock-stepdomain — `step_trajectory_hash` forward stub for the E4
+# cross-PR bridge between PR #278 audit log + PR #279 grammar trajectory.
+# No-op alias today; concrete impl lands once the bridge PR ships.
+trajectory-audit = []