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

Split 876-LOC page.tsx into 146 LOC with 7 colocated components
(RoadmapCard, CreateRoadmapModal, CreateItemModal, ImportWizard,
RoadmapDetailView split into header + items table), plus _types.ts,
_constants.ts, and _api.ts. Behavior preserved.

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

admin-compliance/app/sdk/roadmap/_api.ts

@@ -0,0 +1,13 @@
+export const API_BASE = '/api/sdk/v1/roadmap'
+
+export async function api<T>(path: string, options?: RequestInit): Promise<T> {
+  const res = await fetch(`${API_BASE}${path}`, {
+    headers: { 'Content-Type': 'application/json' },
+    ...options,
+  })
+  if (!res.ok) {
+    const err = await res.json().catch(() => ({ error: res.statusText }))
+    throw new Error(err.error || err.message || `HTTP ${res.status}`)
+  }
+  return res.json()
+}