fix(engine): stop creating nested .fusion/.fusion directory

RoutineStore's constructor appends ".fusion" to its rootDir argument,
but InProcessRuntime was passing taskStore.getFusionDir() (already the
.fusion path), producing <projectRoot>/.fusion/.fusion/fusion.db. Pass
the project root instead, matching AutomationStore's construction.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/engine/src/runtimes/in-process-runtime.ts

@@ -613,7 +613,7 @@ export class InProcessRuntime
         const { RoutineStore: RoutineStoreClass } = await import("@fusion/core");
         // Verify RoutineStore actually has the expected methods (FN-1519 complete)
         if (typeof RoutineStoreClass.prototype.getDueRoutines === "function") {
-          const routineStore = new RoutineStoreClass(this.taskStore.getFusionDir());
+          const routineStore = new RoutineStoreClass(this.config.workingDirectory);
           await routineStore.init();
           this.routineStore = routineStore;