feat(FN-3485): align memory scope guidance and dashboard tooling

- Clarify task memory scope behavior across core types, project memory logic, engine tool prompts, and related docs
- Add regression coverage for memory scope and runtime plugin alias handling in core/dashboard/engine tests
- Add agent avatar API routes and dashboard UI support for avatar display and storage documentation
- Add line-number gutter toggle support in FileEditor and Files modal with accompanying component tests
- Include changeset for @runfusion/fusion documenting memory scope guidance update

Fusion-Task-Id: FN-3485

packages/engine/src/__tests__/heartbeat-executor.test.ts

@@ -622,6 +622,8 @@ describe("executeHeartbeat", () => {
       expect(systemPrompt).toContain("fn_send_message");
       expect(systemPrompt).toContain("fn_memory_search");
       expect(systemPrompt).toContain("fn_memory_append");
+      expect(systemPrompt).toContain('scope="agent"');
+      expect(systemPrompt).toContain('scope="project"');
       expect(systemPrompt).toContain("fn_heartbeat_done");
     });