FN-5674: add per-task auto-merge persistence and resolver

Add per-task auto-merge overrides to the core task model and persist/snapshot them through review transitions.

- add Task.autoMerge typing, storage row mapping, updateTask support, and DB schema migration to persist per-task auto-merge state
- snapshot settings.autoMerge onto tasks when moving into in-review when no explicit task override is set
- export resolveEffectiveAutoMerge to consistently resolve task-level override vs global settings precedence
- expand core tests for migration, persistence, movement, and merge behavior; update roadmap schema-version expectation to match the new schema version

Files changed:
 packages/core/src/__tests__/db-migrate.test.ts     | 10 +++----
 packages/core/src/__tests__/db.test.ts             | 34 +++++++++++-----------
 packages/core/src/__tests__/goals-schema.test.ts   |  2 +-
 packages/core/src/__tests__/insight-store.test.ts  | 10 +++----
 packages/core/src/__tests__/mission-store.test.ts  |  2 +-
 packages/core/src/__tests__/run-audit.test.ts      |  2 +-
 packages/core/src/__tests__/secrets-schema.test.ts |  6 ++--
 .../core/src/__tests__/store-merge-queue.test.ts   |  2 +-
 packages/core/src/__tests__/store-movement.test.ts | 33 +++++++++++++++++++++
 .../core/src/__tests__/store-persistence.test.ts   | 18 ++++++++++++
 packages/core/src/__tests__/task-documents.test.ts |  2 +-
 packages/core/src/__tests__/task-merge.test.ts     | 19 ++++++++++++
 packages/core/src/db.ts                            |  9 +++++-
 packages/core/src/index.ts                         |  1 +
 packages/core/src/store.ts                         | 23 +++++++++++++--
 packages/core/src/task-merge.ts                    | 15 +++++++++-
 packages/core/src/types.ts                         |  7 +++++
 .../src/store/__tests__/roadmap-store.test.ts      |  4 +--
 18 files changed, 157 insertions(+), 42 deletions(-)

Fusion-Task-Id: FN-5674

Fusion-Task-Lineage: 8e1e3988-2e41-4d7a-9653-e88c36ec272c

plugins/fusion-plugin-roadmap/src/store/__tests__/roadmap-store.test.ts

@@ -743,8 +743,8 @@ describe("RoadmapStore", () => {
   });
 
   describe("schema version", () => {
-    it("schema version is 93 after init", () => {
-      expect(db.getSchemaVersion()).toBe(93);
+    it("schema version is 94 after init", () => {
+      expect(db.getSchemaVersion()).toBe(94);
     });
   });