feat: Build Early Access page with backend email capture

Combined page: countdown timer (Feb 28), email capture with server
count segmentation (wired to POST /api/early-access), Founding Admin
Program (25 slots), demo dashboard preview placeholders, roadmap
voting, and launch timeline. Backend: Axum handler, migration for
early_access_signups table with email + server_count + created_at.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/router/index.ts

@@ -164,6 +164,11 @@ const routes: RouteRecordRaw[] = [
         name: 'roadmap',
         component: () => import('@/views/marketing/RoadmapView.vue'),
       },
+      {
+        path: 'early-access',
+        name: 'early-access',
+        component: () => import('@/views/marketing/EarlyAccessView.vue'),
+      },
     ],
   },