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

docs/agents.md

@@ -167,6 +167,9 @@ When engine sessions include per-agent memory context, the memory tools operate
 
 Runtime behavior:
 
+- `fn_memory_append` supports dual scope writes:
+  - `scope="agent"` for private per-agent operating context (personal playbooks/checklists, self-management notes)
+  - `scope="project"` for shared repo-wide durable knowledge (architecture constraints, conventions, pitfalls)
 - `fn_memory_search` can surface snippets from:
   - `.fusion/agent-memory/{agentId}/MEMORY.md` (long-term)
   - `.fusion/agent-memory/{agentId}/DREAMS.md` (synthesized patterns)