Add cache-busting for JS/WASM assets, WASM readiness signaling to JS, and robust fetch with cache control. Improve lobby updates and refine WebSocket logic.

Dockerfile

@@ -1,8 +1,8 @@
 # Stage 1: Builder
 FROM golang:1.25.5-alpine AS builder
 
-# Build-Dependencies
-RUN apk add --no-cache git
+# Build-Dependencies (bash für das Cache-Version-Skript)
+RUN apk add --no-cache git bash sed
 
 WORKDIR /app
 
@@ -21,6 +21,10 @@ RUN if [ ! -f cmd/client/web/assets/assets.json ]; then \
         echo "✅ Assets bereits vorhanden"; \
     fi
 
+# Cache-Version aktualisieren (für Browser-Cache-Busting)
+RUN chmod +x scripts/cache-version.sh && \
+    ./scripts/cache-version.sh
+
 # Server binary bauen
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -installsuffix cgo -ldflags="-w -s" -o server ./cmd/server