M6.3 follow-up — route 5 Lucide icons through design-system/icons wrapper

[vgtray]

Follow-up flagged by dev-frontend-tree during the ISA-95 tree view refactor of the equipment picker (PR #71, commit aa67504).

Problem

`frontend/src/app/EquipmentPicker.tsx` imports 5 Lucide icons directly from `lucide-react`:

• `Building2` (Enterprise)
• `MapPin` (Site)
• `Layers` (Area)
• `GitBranch` (Line)
• `Cpu` (Cell)

The dev kept strokeWidth 1.75 manually on each usage, but this bypasses the centralized `design-system/icons.tsx` wrapper that normally enforces stroke-width and lets us re-theme/replace icons globally. Contravenes `DESIGN_PLAN_v2.md` §7.

Expected

Re-export these 5 icons through `frontend/src/design-system/icons.tsx` (same pattern as `ChevronDown`, `Search`, `X`, `Check`, `RefreshCw` already exposed there), then switch `EquipmentPicker.tsx` to `Icons.Building2` / `Icons.MapPin` / `Icons.Layers` / `Icons.GitBranch` / `Icons.Cpu`.

Files

• `frontend/src/design-system/icons.tsx` (add 5 re-exports)
• `frontend/src/app/EquipmentPicker.tsx` (switch import + usage)

Acceptance

• `grep -n "from \"lucide-react\"" frontend/src/app/EquipmentPicker.tsx` returns empty
• Tree view visual unchanged
• Quality gates still green (typecheck / build / check)

Scope

~10 lines across 2 files. Not blocking the PR #71 merge.

Labels

frontend