refactor: full codebase overhaul — dead code removal, env validation, logger migration, date consolidation, Prisma schema cleanup, button consistency, useEffect deps, test coverage

- env.ts: added 10 missing Zod-validated env vars (imager, paypal currency, argon2/bcrypt params)
- Migrated 6 modules from process.env to validated env.* (auth, proxy-auth, paypal, password, redis, imager, moderation, alert, logger)
- Replaced console.warn/error with pino logger in 9 server-side modules
- Removed 50+ dead exports (SWF wrappers, coalesceHotelName, signIn, isStaff re-export, formatTimestamp, Skeleton/SkeletonCard, 4 unused housekeeping sections)
- Consolidated date formatting: 28 files migrated to shared formatDate() from @/lib/format-date
- Wired 4 radio/settings API routes through cached siteSettings service instead of raw Prisma queries
- Added getMany()/getAll() helpers to SiteSettings service
- Removed 88 dead Prisma model definitions (schema 2763→1846 lines)
- Created admin action-helper.ts with wrapAction() for standardized error handling
- Fixed useEffect dependency arrays in 4 data-heavy components
- Replaced raw btn CSS classes with shadcn Button component across admin pages
- Stripped dead i18n namespaces (common, pages.client) from all 22 translation files
- Removed 2 dead scripts (create-release.sh, check-local-imports.ts)
- Fixed knip.json configuration
- Added 7 new test suites: format-date, paypal, moderation, alert, webhook, action-helper, and fixed password.test.ts for env mocking
- All 358 tests passing across 72 test files
- TypeScript: 0 errors

src/messages/sk.json

@@ -36,11 +36,6 @@
   "footer": {
     "copyright": "© {year} - {hotel} je neziskový vzdelávací projekt"
   },
-  "common": {
-    "language": "Jazyk",
-    "lightMode": "Svetelný režim",
-    "darkMode": "Tmavý režim"
-  },
   "pages": {
     "staff": {
       "title": "personál",
@@ -189,7 +184,7 @@
       "newsTitle": "Najnovšie správy",
       "newsSubtitle": "Čerstvé z hotela",
       "allNews": "Všetky novinky →",
-			"allUsers": "Komunita →",
+      "allUsers": "Komunita →",
       "noArticles": "Zatiaľ žiadne články.",
       "noPhotos": "Zatiaľ žiadne fotky.",
       "noUsers": "Žiadni používatelia online",
@@ -650,21 +645,6 @@
         "error": "Something went wrong. Please try again."
       }
     },
-    "client": {
-      "title": "Nitro klient",
-      "loading": "Načítava sa klient…",
-      "generatingTicket": "Generuje sa tiket SSO…",
-      "connected": "Pripojené",
-      "welcome": "Vitajte v {hotel}",
-      "openingClient": "Otvára sa klient na novej karte…",
-      "fallbackLink": "Ak sa neotvorí,",
-      "fallbackClick": "kliknite sem",
-      "errors": {
-        "unauthorized": "Pre otvorenie klienta musíte byť prihlásený.",
-        "generic": "Lístok SSO sa nepodarilo vygenerovať",
-        "loginRedirect": "Prihláste sa"
-      }
-    },
     "radioApply": {
       "title": "Prihláste sa ako Rádio DJ",
       "subtitle": "Povedzte nám o sebe a o tom, prečo by ste sa skvele hodili do éteru",
@@ -709,7 +689,8 @@
       "securityTitle": "Bezpečnosť",
       "securitySubtitle": "Dvojfaktorové overenie",
       "securityDescription": "Pridajte do svojho účtu druhú vrstvu ochrany.",
-      "twoFactorLink": "Dvojfaktorové overenie"},
+      "twoFactorLink": "Dvojfaktorové overenie"
+    },
     "settings2fa": {
       "backToSettings": "← Nastavenia",
       "title": "Dvojfaktorové overenie",
@@ -731,10 +712,10 @@
       "enableIntro": "Pridajte druhú vrstvu zabezpečenia pomocou autentifikačnej aplikácie.",
       "enable": "Povoliť 2FA"
     },
-      "title": "Prepojené účty",
-      "subtitle": "Prepojte sociálny účet, aby ste sa mohli prihlásiť jedným kliknutím",
-      "connected": "Pripojené",
-      "unavailable": "nedostupné",
+    "title": "Prepojené účty",
+    "subtitle": "Prepojte sociálny účet, aby ste sa mohli prihlásiť jedným kliknutím",
+    "connected": "Pripojené",
+    "unavailable": "nedostupné",
     "login": {
       "title": "Prihláste sa",
       "subtitle": "Vitajte späť — prihláste sa pre vstup do hotela.",