feat(cms): enable Payload localization — hu default + en (MITHOME-110)

payload.config.ts: localization: { locales: ['hu','en'], defaultLocale:
'hu', fallback: true }. URL/routing side is separate (MITHOME-114).

Proved the mechanism on a real field rather than a throwaway one:
Common.buttons.* (contact/learnMore/webmail/sendMessage) marked
localized: true — these are genuinely translatable UI labels, so this
doubles as a first, correct slice of the full MITHOME-111 retrofit
instead of being disposable test scaffolding.

Gotcha discovered and documented in the migration script: marking an
existing field `localized: true` after data was already written non-
localized makes that value unreadable via `locale: defaultLocale` (the
storage shape changed) — the migration script must be re-run so it
gets rewritten under the localized shape. This will matter again for
the full MITHOME-111/112 retrofit.

Verified: Local API round-trip (set en, defaultLocale/hu re-seeded via
re-running the migration script) — hu reads "Kapcsolatfelvétel", en
reads "Contact". Real browser: admin UI locale switcher (hu/en) in the
top bar, fields show "— hu"/"— en" per-locale labels, switching
locale swaps the visible value correctly on the Common global editor.
build/lint/tsc/test (58 passed) all clean.

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

proto/src/payload.config.ts

@@ -11,6 +11,9 @@
  * feltetelek).
  * MITHOME-89: Partners + Media collection (MVP — feltöltés, a vágás/
  * áttetszővé tétel szerkesztő külön, MITHOME-118).
+ * MITHOME-110: lokalizáció bekapcsolva (hu alapértelmezett, en). A mezőnkénti
+ * `localized: true` retrofit a Globals/LegalPages configokon külön ticket
+ * (MITHOME-111/112) — ez a ticket csak magát a mechanizmust kapcsolja be.
  */
 import path from 'path'
 import { fileURLToPath } from 'url'
@@ -45,6 +48,15 @@ export default buildConfig({
 
   globals: [Home, About, Services, Contact, Common],
 
+  // MITHOME-109/110: hu alapértelmezett (URL-prefix nélkül), en /en/ alatt
+  // (Next.js routing oldala: MITHOME-114). fallback:true -> amíg egy mezőnek
+  // nincs angol fordítása, a magyar érték jelenik meg — nem üres oldal.
+  localization: {
+    locales: ['hu', 'en'],
+    defaultLocale: 'hu',
+    fallback: true,
+  },
+
   secret: process.env.PAYLOAD_SECRET || '',
 
   typescript: {