fix(FN-680): restore TaskStore project resolution and fresh schema writes

- fix TaskStore.getOrCreateForProject to resolve projects through BackwardCompat and support legacy .fusion/.kb detection
- add regression tests for exact-name project lookup, legacy cwd fallback, and fresh-schema task create/update persistence
- sync the tasks schema definition with missionId support so fresh databases match runtime migrations
- add project overview and selector styles for the multi-project dashboard UI

packages/core/src/db.ts

@@ -161,6 +161,7 @@ CREATE TABLE IF NOT EXISTS tasks (
   breakIntoSubtasks INTEGER DEFAULT 0,
   enabledWorkflowSteps TEXT DEFAULT '[]',
   modifiedFiles TEXT DEFAULT '[]',
+  missionId TEXT,
   sliceId TEXT
 );