ci: switch to Gitea Container Registry for reliable deploys

Previous pipeline built images locally via Portainer Docker API,
but Docker layer caching produced identical images. Now:
- Build with nocache=1
- Push to Gitea registry (git.home.rm-warpstation.de)
- Compose uses image: from registry instead of build:
- Redeploy with pullImage: true forces fresh container

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

frontend/src/hooks/useRankChange.js

@@ -1,9 +1,13 @@
 import { useState, useEffect } from 'react';
 import { api } from '../api/client';
 const RANK_KEY = 'tippspiel_last_rank';
+const SHOWN_KEY = 'tippspiel_rank_toast_shown';
 export function useRankChange() {
     const [message, setMessage] = useState(null);
     useEffect(() => {
+        // Only show once per session
+        if (sessionStorage.getItem(SHOWN_KEY))
+            return;
         api.getMyStats().then(stats => {
             if (!stats.rank)
                 return;
@@ -15,6 +19,7 @@ export function useRankChange() {
                 else {
                     setMessage(`⬇️ Du bist auf Platz ${stats.rank} gerutscht — hol dir die Punkte zurück!`);
                 }
+                sessionStorage.setItem(SHOWN_KEY, '1');
             }
             localStorage.setItem(RANK_KEY, String(stats.rank));
         }).catch(() => { });