feat: export a import kampani a cenoviek pre prenos na novy server

- npm run db:export: kampane a sablony cenoviek do supabase/data/ (+ obrazky z uloziska)
- npm run db:import [-- --dry-run]: nahra data s povodnymi ID, prepise odkazy
  na nove ulozisko, da sa spustit opakovane
- aktualny export: 7 kampani, 1 sablona cenovky

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -7,7 +7,9 @@
     "build": "next build",
     "start": "next start",
     "lint": "eslint",
-    "db:upload-assets": "node --env-file=.env.local scripts/upload-assets.mjs"
+    "db:upload-assets": "node --env-file=.env.local scripts/upload-assets.mjs",
+    "db:export": "node --env-file=.env.local scripts/export-data.mjs",
+    "db:import": "node --env-file=.env.local scripts/import-data.mjs"
   },
   "dependencies": {
     "@supabase/supabase-js": "^2.117.1",