FN-8771: fix PostgreSQL workflow fixture import

Use the canonical workflow module in PostgreSQL mission-store fixture coverage.

- Import the built-in coding workflow IR from its dedicated workflow module.
- Document the schema/workflow API boundary for renamed-lane coverage.

Files changed:
 packages/core/src/__tests__/postgres/mission-store.pg.test.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Fusion-Task-Id: FN-8771

Fusion-Task-Lineage: d287a0fa-5d79-4784-8576-cc6b3d788258

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

packages/core/src/__tests__/postgres/mission-store.pg.test.ts

@@ -37,7 +37,7 @@ import {
   listMissions as listMissionRows,
   updateMilestoneValidationState,
 } from "../../async-stores/async-mission-store.js";
-import { BUILTIN_CODING_WORKFLOW_IR } from "../../postgres/schema/index.js";
+import { BUILTIN_CODING_WORKFLOW_IR } from "../../workflows/builtin-coding-workflow-ir.js";
 
 const pgTest = pgDescribe;
 
@@ -413,6 +413,12 @@ pgTest("MissionStore (PostgreSQL backend mode)", () => {
   render, from a path that runs during ordinary feature bootstrap.
 
   DIFFERENTIAL: `filed` collides with no legacy id, so a surviving `"archived"` cannot pass by luck.
+
+  FNXC:WorkflowResolvedColumns 2026-08-03-23:52:
+  This fixture imports the canonical workflow module directly. The PostgreSQL schema barrel is only
+  the Drizzle table contract and deliberately does not re-export workflow definitions; sibling
+  renamed-lane PostgreSQL coverage uses the same direct source to keep schema and workflow APIs
+  separate.
   */
   it("archives a bootstrap duplicate into the RENAMED archive lane", async () => {
     const m = missions();