Add HTTPS support in dev mode and fix mobile layout issues

Generate self-signed certs for local HTTPS, add port 443 and full SSL
server block to dev nginx config, add Spotify redirect URI env var,
improve Spotify token error handling, and fix Chat/Steam mobile sizing.

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

nginx/Dockerfile

@@ -1,6 +1,6 @@
 FROM nginx:latest
 RUN rm -rf /etc/nginx/html/* && \
-    apt-get update && apt-get install -y gettext-base && \
+    apt-get update && apt-get install -y gettext-base openssl && \
     rm -rf /var/lib/apt/lists/*
 COPY nginx.conf.template /etc/nginx/nginx.conf.template
 COPY nginx_setup.conf.template /etc/nginx/nginx_setup.conf.template