feat(conversions): end-to-end PPT/PPTX/ODP -> PDF pipeline with RQ worker + Gotenberg

DB/model

Add Conversion model + ConversionStatus enum (pending, processing, ready, failed)
Alembic migrations: create conversions table, indexes, unique (source_event_media_id, target_format, file_hash), and NOT NULL on file_hash
API

Enqueue on upload (ppt|pptx|odp) in routes/eventmedia.py: compute sha256, upsert Conversion, enqueue job
New routes:
POST /api/conversions/<media_id>/pdf — ensure/enqueue conversion
GET /api/conversions/<media_id>/status — latest status/details
GET /api/files/converted/<path> — serve converted PDFs
Register conversions blueprint in wsgi
Worker

server/worker.py: convert_event_media_to_pdf
Calls Gotenberg /forms/libreoffice/convert, writes to server/media/converted/
Updates Conversion status, timestamps, error messages
Fix media root resolution to /server/media
Prefer function enqueue over string path; expose server.worker in package init for RQ string compatibility
Queue/infra

server/task_queue.py: RQ queue helper (REDIS_URL, default redis://redis:6379/0)
docker-compose:
Add redis and gotenberg services
Add worker service (rq worker conversions)
Pass REDIS_URL and GOTENBERG_URL to server/worker
Mount shared media volume in prod for API/worker parity
docker-compose.override:
Add dev redis/gotenberg/worker services
Ensure PYTHONPATH + working_dir allow importing server.worker
Use rq CLI instead of python -m rq for worker
Dashboard dev: run as appropriate user/root and pre-create/chown caches to avoid EACCES
Dashboard dev UX

Vite: set cacheDir .vite to avoid EACCES in node_modules
Disable Node inspector by default to avoid port conflicts
Docs

Update copilot-instructions.md with conversion system: flow, services, env vars, endpoints, storage paths, and data model

dashboard/vite.config.ts

@@ -4,6 +4,7 @@ import react from '@vitejs/plugin-react';
 
 // https://vite.dev/config/
 export default defineConfig({
+  cacheDir: './.vite',
   plugins: [react()],
   resolve: {
     // 🔧 KORRIGIERT: Entferne die problematischen Aliases komplett