feat(FN-3530): add modal-based agent error details and UI/docs updates

- 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

packages/dashboard/README.md

@@ -264,6 +264,7 @@ Manage AI agents with a dedicated control surface accessible from the main dashb
 - **View Modes**: Board (compact grid) and list (detailed card) layouts, persisted to localStorage
 - **Agent CRUD**: Create agents with name and role (create form's text input and role/type select both use tokenized styling — `var(--surface)`, `var(--text)`, `var(--border)`, `var(--radius-sm)`, `var(--focus-ring)` — for consistent theme-aware rendering across all color themes and light/dark modes), change state, update roles inline, delete idle and terminated agents (active and paused agents must be stopped/terminated first)
 - **Health Monitoring**: Heartbeat-based health status (Healthy, Unresponsive, Starting, Paused, Terminated) using CSS variable references for theme consistency
+- **Agent Error Details**: Agent collection views now show a compact inline error indicator (instead of raw stack traces) that opens a shared error-details modal with full text, copy action, and a prefilled "Report on GitHub" shortcut
 - **Agent Detail**: Click any agent card to open a detail modal with full agent information. In list view, each agent card also provides an explicit **View Details** action button in the card actions row for clearer discoverability, while the existing clickable identity/header area remains supported. The modal features a compact header with clear visual hierarchy:
   - **Identity area** (left): Agent icon, name, and state/health badges
   - **Lifecycle controls** (center): Compact action buttons for state transitions (Start, Pause, Resume, Retry, Stop, Delete)