pg-delta: order RLS policies after referenced new tables

[avallete]

Problem

When planning or applying declarative changes, an RLS policy on one new table can reference another new table inside USING or WITH CHECK. If pg-delta emits CREATE POLICY before the referenced table exists, plan/apply fails on an empty database.

Current gaps

• Integration coverage appears to focus on self-table policies and simpler create-table-plus-policy cases, not policies whose expressions reference another newly created table.
• Dependency / sort logic does not obviously treat "policy expression references table X" as an ordering edge, so cross-table references may not influence plan order.

Suggested direction

1. Add a regression test that creates two new tables and a policy on one table whose USING/WITH CHECK references the other.
2. Prefer extending dependency extraction so policies depend on newly created tables referenced in those expressions.
3. If expression-based edges are not practical in the short term, add a narrow deferral step for policy creation after referenced new relations exist.

Success criteria

• The failing case is covered by integration tests.
• Plan/apply produces a valid order for cross-table policy references on a fresh database.

[avallete]

One extra regression shape from the benchmark notes: the cross-table policy predicate used a more complex USING clause than the simple EXISTS example, with IN (SELECT ...) against another new table plus additional filtering logic. If dependency extraction is fully generic over table references inside policy expressions, the current test in #187 may already be enough; if not, that richer predicate would make a good second regression case. For context only: pgschema #373 / #374.