Add image compression to Dockerfile using optipng and jpegoptim for optimized asset handling; update build dependencies.

Dockerfile

@@ -1,8 +1,8 @@
 # Stage 1: Builder
 FROM golang:1.25.5-alpine AS builder
 
-# Build-Dependencies (bash für das Cache-Version-Skript)
-RUN apk add --no-cache git bash sed
+# Build-Dependencies (bash für das Cache-Version-Skript + optipng/jpegoptim für Bildkompression)
+RUN apk add --no-cache git bash sed optipng jpegoptim
 
 WORKDIR /app
 
@@ -25,6 +25,12 @@ RUN if [ ! -f cmd/client/web/assets/assets.json ]; then \
 RUN chmod +x scripts/cache-version.sh && \
     ./scripts/cache-version.sh
 
+# Bilder komprimieren (verlustfrei für PNG, leichter Verlust für JPG)
+RUN echo "🗜️ Komprimiere Bilder..." && \
+    find cmd/client/web -type f -name "*.png" -exec optipng -o2 -strip all {} \; && \
+    find cmd/client/web -type f \( -name "*.jpg" -o -name "*.jpeg" \) -exec jpegoptim --strip-all -m85 {} \; && \
+    echo "✅ Bildkompression abgeschlossen"
+
 # Server binary bauen
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -installsuffix cgo -ldflags="-w -s" -o server ./cmd/server