V1.5.0: Version bump + Download-Button Redesign

- Version auf 1.5.0 in allen Packages, CI, Dockerfile, Electron
- Download-Button im gleichen Design wie Version-Badge (bg-secondary, radius, hover accent)
- CI Registry auf adriahub (192.168.1.100:9080) umgestellt

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "gaming-hub-server",
-  "version": "1.0.0",
+  "version": "1.5.0",
   "type": "module",
   "scripts": {
     "build": "tsc",