fix(FN-915): use getFusionDir() for agent storage location

- Add getFusionDir() method to TaskStore for resolving agent database path
- Update in-process-runtime to use getFusionDir() instead of hardcoded path
- Update dashboard routes AgentStore initialization to use getFusionDir()
- Add changeset for published package patch bump

packages/core/src/store.ts

@@ -2744,6 +2744,11 @@ ${stepsSection}`;
     return this.rootDir;
   }
 
+  /** Return the `.fusion` directory path (e.g. `/project/.fusion`). */
+  getFusionDir(): string {
+    return this.kbDir;
+  }
+
   getTasksDir(): string {
     return this.tasksDir;
   }