fix(FN-2148): use hash cache-busting and fix store teardown

- Switch PluginLoader bypass-cache imports from a query string to a hash fragment for reload-safe module differentiation
- Update inline documentation to reflect hash-based cache busting semantics in Node ESM imports
- Close AgentStore in the affected agent-store test afterEach hook to ensure cleanup alongside TaskStore teardown

packages/core/src/agent-store.test.ts

@@ -1508,6 +1508,7 @@ describe("AgentStore", () => {
     });
 
     afterEach(() => {
+      store.close();
       taskStore.close();
     });
 

packages/core/src/plugin-loader.ts

@@ -269,9 +269,9 @@ export class PluginLoader extends EventEmitter<{
     // Dynamic import - use cache-busting for reload scenarios
     let mod: unknown;
     if (bypassCache) {
-      // Use cache-busting with timestamp for ESM modules
-      // This ensures Node.js re-imports the module even if it has it cached
-      const bustedPath = `${path}?reload=${Date.now()}`;
+      // Use a hash fragment for cache differentiation without affecting path resolution
+      // Node treats each distinct URL as a fresh import while resolving the same file path
+      const bustedPath = `${path}#${Date.now()}`;
       mod = await import(bustedPath);
     } else {
       mod = await import(path);