feat(FN-1567): add mission contract assertions model types and APIs

- Add mission contract assertions model with types: ContractAssertion, ContractAssertionStatus, ContractAssertionType
- Add assertions table to schema v29 with migration from v28
- Implement assertion APIs: create, update, link/unlink to features, list, getWithContext
- Add rollup computation (assertion counts, pass rates) for missions and milestones
- Add many-to-many feature-to-assertion linking via featureAssertions table
- Add project memory documentation for assertion lifecycle and patterns
- Update schema version assertions in db.test.ts, run-audit.test.ts, and task-documents.test.ts

packages/core/src/run-audit.test.ts

@@ -465,7 +465,7 @@ describe("Run Audit", () => {
     });
 
     it("schema version is bumped to 28", () => {
-      expect(db.getSchemaVersion()).toBe(28);
+      expect(db.getSchemaVersion()).toBe(29);
     });
   });
 });