feat(cms): Home/About/Services/Contact/Common Globals + JSON migration (MITHOME-87)

Payload Global configs mirroring proto/src/content/types.ts:
- src/globals/{Home,About,Services,Contact,Common}.ts
- src/globals/fields/stringArray.ts — shared helper: Payload has no
  native string[] field, so every plain string array from the old
  content types (trustBullets, paragraphs, features, spec items, …)
  becomes an array of one-field { value } objects.
- home.partners is intentionally NOT included — that becomes its own
  Partners collection (logo -> Media upload) in MITHOME-89, to avoid
  two disagreeing sources for the same data.
- contact.form.fields.gdpr.label stays a plain textarea (not lexical
  richText): the JSON source is a hand-written HTML string with an
  <a> tag; richText's node-tree serialization would need its own
  migration/render logic, out of scope for this bootstrap pass.

scripts/migrate-content-to-payload.ts: one-shot, idempotent Local API
migration reading the existing JSON files and calling updateGlobal —
does not touch or delete the JSON files. Run via the new
`npm run migrate:content` script.

Registered the five Globals in payload.config.ts.

Also included here (belongs with the previous "resolve double-root-
layout conflict" commit but didn't actually get staged there —
verified only now by diffing HEAD against the working tree):
(frontend)/layout.tsx's relative imports corrected to ../../ instead
of ../ (one directory deeper than the original src/app/layout.tsx).

Verified:
- npm run build / lint, tsc --noEmit, npm test (58 passed) all clean
- npm run migrate:content against the real dev MongoDB container,
  then read back via payload.findGlobal() — hero.title, trustBullets,
  services.items[0].features, footer.address, faq.items.length all
  match the JSON source
- Real browser: logged into /admin, opened the Home global editor —
  Hero/Trust bullets group renders and shows the migrated Hungarian
  content correctly (see screenshot shared in chat)

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

proto/src/payload.config.ts

@@ -5,11 +5,9 @@
  * (proto/src/lib/mongodb.ts) — Payload a `mongooseAdapter`-en keresztül
  * ugyanabba az adatbázisba ír, nincs szükség külön DB-re/szerverre.
  *
- * Ez a fájl jelenleg csak a bootstrap-hez szükséges minimumot tartalmazza
- * (Users collection az admin bejelentkezéshez — Payload nem tud admin
- * felületet renderelni auth collection nélkül). A tényleges tartalom-
- * collectionök/globalok (Home, About, Services, Contact, Common, LegalPages,
- * Partners, Media) a MITHOME-87..90 ticketekben kerülnek be.
+ * MITHOME-87: Home/About/Services/Contact/Common Globals hozzáadva — ezek
+ * tükrözik a proto/src/content/pages/*.json + common.json struktúráját.
+ * A LegalPages/Partners/Media collectionök a MITHOME-88..89-ben kerülnek be.
  */
 import path from 'path'
 import { fileURLToPath } from 'url'
@@ -19,6 +17,11 @@ import { lexicalEditor } from '@payloadcms/richtext-lexical'
 import sharp from 'sharp'
 
 import { Users } from './collections/Users'
+import { Home } from './globals/Home'
+import { About } from './globals/About'
+import { Services } from './globals/Services'
+import { Contact } from './globals/Contact'
+import { Common } from './globals/Common'
 
 const filename = fileURLToPath(import.meta.url)
 const dirname = path.dirname(filename)
@@ -34,6 +37,8 @@ export default buildConfig({
 
   collections: [Users],
 
+  globals: [Home, About, Services, Contact, Common],
+
   secret: process.env.PAYLOAD_SECRET || '',
 
   typescript: {