feat: harden admin security, add AI trip planner, map view, and SEO/notification improvements

Security:
- requireAdmin() session check added to every admin-only server action
  (previously relied only on middleware path matching, which Next.js
  Server Actions don't reliably respect)
- Real Prisma + bcrypt admin auth, replacing hardcoded credentials; split
  into an Edge-safe auth.config.ts (used by proxy.ts) and the full
  Prisma-backed auth.ts (route handler, server actions, server components)
- Removed hardcoded fallback secret on the Instagram sync cron endpoint
- Honeypot field + per-IP rate limiting on contact/business-submission
  forms and the analytics events endpoint

Features:
- AI trip planner (/plan-olustur, /plan/[id]) backed by DeepSeek, grounded
  to only recommend isLocalApproved listings, with a deterministic
  link-injection fallback for anything the model doesn't format as markdown
- Interactive Leaflet/OpenStreetMap view on category listing pages
- Telegram notifications for new contact messages and business submissions

SEO:
- Brand-consistent favicon/apple-icon/PWA icons and default Open Graph/
  Twitter share images, generated via next/og (replacing default Next.js
  placeholders)
- BreadcrumbList structured data on category and listing detail pages
- Fixed two remaining raw <img> tags to use next/image

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/[locale]/twitter-image.tsx

@@ -0,0 +1,16 @@
+import { ImageResponse } from 'next/og'
+import { OgImageContent } from '@/lib/ogImage'
+
+export const size = { width: 1200, height: 630 }
+export const contentType = 'image/png'
+
+const TAGLINES: Record<string, string> = {
+  tr: 'turistin göremediği yerel bilgi.',
+  en: 'the local knowledge tourists never see.',
+  ru: 'инсайдерская информация, скрытая от туристов.',
+}
+
+export default async function Image({ params }: { params: Promise<{ locale: string }> }) {
+  const { locale } = await params
+  return new ImageResponse(<OgImageContent tagline={TAGLINES[locale] || TAGLINES.tr} />, size)
+}