refactor(admin): split architecture page.tsx into colocated components

Extract DetailPanel, ArchHeader, Toolbar, ArchCanvas and ServiceTable into
_components/, the ReactFlow node/edge builder into _hooks/useArchGraph, and
layout constants/helpers into _layout.ts. page.tsx drops from 950 to 91 LOC,
well below the 300 soft target.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-compliance/app/sdk/architecture/_layout.ts

@@ -0,0 +1,30 @@
+import { ARCH_SERVICES, LAYERS, type ArchService, type ServiceLayer } from './architecture-data'
+
+// =============================================================================
+// TYPES
+// =============================================================================
+
+export type LayerFilter = 'alle' | ServiceLayer
+
+// =============================================================================
+// LAYOUT
+// =============================================================================
+
+export const NODE_WIDTH = 180
+export const NODE_HEIGHT = 70
+export const NODE_X_SPACING = 220
+export const LANE_Y_START = 80
+export const LANE_LABEL_HEIGHT = 40
+
+export const LAYER_ORDER: ServiceLayer[] = ['frontend', 'backend', 'infrastructure', 'data-sovereignty']
+
+export function getServicePosition(service: ArchService): { x: number; y: number } {
+  const layer = LAYERS[service.layer]
+  const layerServices = ARCH_SERVICES.filter(s => s.layer === service.layer)
+  const idx = layerServices.findIndex(s => s.id === service.id)
+
+  return {
+    x: 80 + idx * NODE_X_SPACING,
+    y: LANE_Y_START + LANE_LABEL_HEIGHT + layer.y,
+  }
+}