Initial commit: Visigine (Vite client + Express/SQLite backend)

Container-ready via docker/ compose (frontend nginx + backend Node). Compose adjusted for Coolify on the prod server: frontend uses expose:80 (no host binding — host 8080 is taken by the Coolify proxy; Traefik routes visigine.de), backend ALLOWED_ORIGINS=https://visigine.de. Secrets stay in server/.env (git-ignored); see server/.env.example.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/checks/technical.js

@@ -0,0 +1,51 @@
+// Group E — technical signals: sitemap, HSTS, viewport, H1.
+export async function runTechnicalChecks({ baseUrl, html, headHtml, robotsTxt, responseHeaders, fetchPage }) {
+  const rb = robotsTxt || ''
+  const hh = headHtml || ''
+  const full = html || ''
+  const headers = responseHeaders || {}
+
+  let sitemapReachable = false
+  try {
+    const sm = await fetchPage(`${baseUrl}/sitemap.xml`)
+    const body = (sm.body || '').trimStart()
+    sitemapReachable =
+      sm.status === 200 &&
+      (body.startsWith('<?xml') || body.startsWith('<urlset') || body.startsWith('<sitemapindex'))
+  } catch {
+    sitemapReachable = false
+  }
+
+  return [
+    {
+      id: 'tech.sitemap-referenced',
+      title: 'Sitemap in robots.txt nicht referenziert',
+      severity: 'low',
+      passed: /sitemap:/i.test(rb),
+    },
+    {
+      id: 'tech.sitemap-reachable',
+      title: 'Sitemap.xml nicht erreichbar',
+      severity: 'medium',
+      passed: sitemapReachable,
+    },
+    {
+      id: 'tech.hsts',
+      title: 'HSTS-Header fehlt',
+      severity: 'low',
+      passed: Boolean(headers['strict-transport-security']),
+    },
+    {
+      id: 'tech.viewport',
+      title: 'Viewport-Meta-Tag fehlt (Mobile)',
+      severity: 'medium',
+      passed: /name=["']viewport["']/i.test(hh),
+    },
+    {
+      id: 'tech.h1',
+      title: 'H1-Überschrift fehlt',
+      severity: 'medium',
+      passed: /<h1[\s>]/i.test(full),
+    },
+  ]
+}