Merges FN-4015 to add stale module-resolution incident detection and self-healing in the engine (`transient-error-detector.ts`, `self-healing.ts`) with mobile regression coverage for the shared `AgentErrorDetailsModal` layout.
Fusion-Task-Id: FN-4015
- Update AgentErrorDetailsModal styles to improve mobile layout and avoid viewport overflow
- Add mobile regression tests for agent modal behavior in agent-modals-mobile coverage
- Extend core modal mobile test suite with AgentErrorDetailsModal safeguards
Fusion-Task-Id: FN-3587
- Add AgentErrorDetailsModal and wire agent list/detail views to open full error diagnostics while keeping inline errors compact
- Add line-number gutter toggle in FileEditor and Files modal with dashboard persistence coverage
- Align project memory scope guidance across core logic, CLI tool docs, and dashboard docs
- Add regression coverage for runtime plugin alias behavior and update related engine/heartbeat tests
- Include changesets for FN-3530 UI improvements and FN-3485 memory guidance updates
Fusion-Task-Id: FN-3530
