chore(rebrand): rename WatchStack -> Quivio

Quivio (Kofferwort aus Quire + Video) ersetzt den Arbeitstitel WatchStack.
Es ist origineller, frei auf PyPI/npm, und passt perfekt zur Doppelnatur
der App: Buecher (Quire) + Serien (Video).

Geaendert:
- Python-Paket app/ -> quivio/ (+ alle Imports angepasst)
- DB-File watchstack.db -> quivio.db
- Docker-Image: quivio:0.5.1-beta, Container-Name quivio
- Compose-Services: quivio, quivio-local
- ENV-Vars: QUIVIO_VERSION, QUIVIO_PORT, Volume quivio-data
- Frontend-Logo "W" -> "Q", Titel "Quivio", Footer
- Favicon "Q" (Georgia serif fuer klassischen Look)
- Logger-Name: watchstack -> quivio
- README, NOTICE, dist/README, data/README: Quivio
- CI-Workflow: testet quivio/ Pfade
- build-and-push.sh: lokaler Tag "quivio:VERSION"
- service-Feld in /api/health: quivio
- OpenAPI title: Quivio

Bugfix (gefunden beim Renaming):
- seed.py hatte versteckten "from app.database import DB_PATH" — gefixt

Verifiziert end-to-end:
- Python-Import OK
- Backend: service=quivio, version=0.5.1-beta, 8 unique items
- Docker-Build OK, Push in Gitea-Registry OK (neuer sha256-Digest)
- Container: Quivio 0.5.1-beta ready (logger), HTML ohne WatchStack-Rest
- OpenAPI title=Quivio
- 8 unique items nach cold start (Race-Fix haelt)

bin/build-and-push.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
-# Baut das Image und pusht es in die Gitea Container Registry.
+# Baut das Quivio-Image und pusht es in die Gitea Container Registry.
 # Verwendung:
-#   bin/build-and-push.sh                # Version aus app/__init__.py
+#   bin/build-and-push.sh                # Version aus quivio/__init__.py
 #   VERSION=0.6.0 bin/build-and-push.sh  # explizite Version
 #   bin/build-and-push.sh --load         # baut + laedt nur (kein Push)
 set -euo pipefail
@@ -16,7 +16,7 @@ fi
 REGISTRY="${REGISTRY:-git.pkop.de}"
 OWNER_LC=$(echo "${OWNER:-Vibecode}" | tr '[:upper:]' '[:lower:]')
 REPO_LC=$(echo "${REPO:-watchlist}"  | tr '[:upper:]' '[:lower:]')
-LOCAL_TAG="watchstack:${VERSION}"
+LOCAL_TAG="quivio:${VERSION}"
 REMOTE_TAG="${REGISTRY}/${OWNER_LC}/${REPO_LC}:${VERSION}"
 
 echo ">> Building ${LOCAL_TAG}"
@@ -35,4 +35,4 @@ docker push "${REMOTE_TAG}"
 
 echo ">> Done."
 echo "   Pull with: docker pull ${REMOTE_TAG}"
-echo "   Run with:  docker run -d --name watchstack -p 8000:8000 -v watchstack-data:/data ${REMOTE_TAG}"
+echo "   Run with:  docker run -d --name quivio -p 8000:8000 -v quivio-data:/data ${REMOTE_TAG}"