Fix: Revert to inline shared types (Turbopack can't resolve path aliases)

Turbopack doesn't support tsconfig path aliases pointing outside
the project root. Reverted to copying shared types directly into
each service. The canonical source remains shared/types/*.ts,
synced via scripts/sync-shared-types.sh.

Changes:
- Reverted docker-compose.yml contexts to ./service
- Reverted Dockerfiles to simple COPY . .
- Removed @shared/* from tsconfigs
- Removed symlinks + .gitignore hacks
- Added scripts/sync-shared-types.sh for keeping copies in sync

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-lehrer/app/(admin)/education/klausur-korrektur/_components/types.ts

@@ -8,4 +8,4 @@ export type {
   VorabiturEHForm,
   EHTemplate,
   DirektuploadForm,
-} from '@shared/types/klausur'
+} from '../../types'