Add mobile view-only support

Below md width, the app now forces view-only (same canEdit mechanism as a
shared view-only diagram) rather than trying to support touch editing:
palette and inspector panels hide, editing controls disable, and the top
bar collapses to just Diagrams + Account. A bottom tab bar swaps between a
full-screen canvas and a full-screen Bill of Materials, since there's no
room for both side by side. Canvas gets a few mobile-specific trims too:
MiniMap and the interactivity lock button hide whenever canEdit is false
(the lock button doesn't actually grant editing either way — nodesDraggable/
nodesConnectable already override it — so leaving it visible would just be
misleading), and h-screen is replaced with h-dvh throughout so the layout
doesn't get clipped by a mobile browser's collapsing address bar.

Also fixes quick-add's anti-stack offset (24px — far smaller than a device
node) to actually tile devices apart instead of leaving them nearly
overlapping, and logs a deferred "Auto-arrange" layout feature in
organized-ideas.md, surfaced by mobile visitors having no way to fix an
overlapping diagram themselves.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017DUU6CnxECCDeqDNYJgr5x

src/components/inspector/DeviceInspector.tsx

@@ -4,14 +4,14 @@ import { allPortTypes } from '../../domain/diagram'
 import type { PortDirection } from '../../domain/types'
 import { useCatalogStore } from '../../state/catalogStore'
 import { useDiagramStore } from '../../state/diagramStore'
+import { useCanEdit } from '../../hooks/useCanEdit'
 import CategorySelect from '../common/CategorySelect'
 import ManufacturerSelect from '../common/ManufacturerSelect'
 
 export default function DeviceInspector({ deviceId }: { deviceId: string }) {
   const diagram = useDiagramStore((s) => s.diagram)
   const catalog = useCatalogStore((s) => s.catalog)
-  const access = useDiagramStore((s) => s.access)
-  const canEdit = access?.myPermission !== 'view'
+  const canEdit = useCanEdit()
   const updateDevice = useDiagramStore((s) => s.updateDevice)
   const removeDevice = useDiagramStore((s) => s.removeDevice)
   const addPort = useDiagramStore((s) => s.addPort)