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/entrypoint.sh

@@ -3,7 +3,15 @@ set -e
 
 # Check if dev mode, certificate exists, or setup mode
 if [ "$DEV_MODE" = "true" ]; then
-  echo "Dev mode. Using HTTP-only nginx config."
+  echo "Dev mode. Generating self-signed certificate for HTTPS."
+  CERT_DIR="/etc/letsencrypt/live/localhost"
+  if [ ! -f "$CERT_DIR/fullchain.pem" ]; then
+    mkdir -p "$CERT_DIR"
+    openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
+      -keyout "$CERT_DIR/privkey.pem" \
+      -out "$CERT_DIR/fullchain.pem" \
+      -subj "/CN=localhost" 2>/dev/null
+  fi
   envsubst '${DOMAIN} ${BACKEND_HOST} ${BACKEND_PORT} ${BACKEND_ENDPOINT} ${ICECAST_HOST} ${ICECAST_PORT} ${GITEA_HOST} ${GITEA_PORT}' \
     </etc/nginx/nginx_dev.conf.template \
     >/etc/nginx/nginx.conf