fix(openbuilt-templates-marketplace): critical companion-schema target + owner field + quality

CRITICAL FIXES (from architect review of WIP commit 81be0a4):

1. Companion schemas were being saved into the Application schema (line 168
   of WIP), as if they were Applications. Replaced with the hybrid register
   model from locked decisions: cloned user schemas now land in a per-app
   `openbuilt-{newSlug}` register via SchemaMapper::createFromArray() +
   RegisterMapper::createFromArray()/update(); ApplicationTemplate continues
   to live in the shared `openbuilt` register.

2. New Application records had no owner/uid. Added explicit `owner` field
   (the caller's UID via IUserSession) and scoped the slug-collision check
   to that owner so multi-user isolation works.

QUALITY:

- PHPCBF auto-fixed 25 PHPCS violations across controller + seed step.
- Removed 2 remaining inline ternaries flagged by PHPCS.
- Extracted createFromTemplate() into 5 focused helpers (errorResponse,
  resolveSharedContext, buildClonedManifest, provisionPerAppArtifacts,
  persistApplication) so NPath/method-length pass PHPMD.
- Imported RuntimeException + Throwable in SeedApplicationTemplates to
  clear PHPMD MissingImport.
- Refactored SeedApplicationTemplates to use ObjectService directly with
  register/schema slugs, matching the bootstrap SeedHelloWorld pattern.

PLAIN-ENGLISH I18N (locked decision):

- Replaced all `openbuilt.templates.*` i18n keys in the 4 seeded template
  fixtures with plain English strings.
- Dropped the i18n key block from l10n/en.json + l10n/nl.json (kept the
  gallery UI strings + category labels).

DOCS:

- Added `owner` + `templateOrigin` fields to the Application schema in
  openbuilt_register.json.
- Added the ApplicationTemplate schema TO the register (didn't replace it).

Spec/contract dependency: clone targets the OR runtime schema API. If the
live API moves, target = `POST /apps/openregister/api/registers/openbuilt-
{newSlug}/schemas` per chain spec #3.

Author: rubenvdlinde