Clean up the dockerfile a bit

entrypoint.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+# Substitute the real config into the prebuilt frontend bundle, then run the
+# backend and static server, exiting (so the orchestrator restarts us) if either
+# process dies.
+set -euo pipefail
+
+# Map the provided runtime variables onto the frontend's VITE_* placeholders.
+VITE_API_URL="${SERVER_URL:-}"
+VITE_RELAY_DOMAIN="${RELAY_DOMAIN:-}"
+VITE_PLATFORM_NAME="${PLATFORM_NAME:-}"
+
+# Escape characters that are special in a sed replacement.
+esc() { printf '%s' "$1" | sed -e 's/[&|\\]/\\&/g'; }
+
+echo "Applying runtime configuration to the frontend bundle..."
+while IFS= read -r -d '' f; do
+  sed -i \
+    -e "s|__VITE_API_URL__|$(esc "$VITE_API_URL")|g" \
+    -e "s|__VITE_RELAY_DOMAIN__|$(esc "$VITE_RELAY_DOMAIN")|g" \
+    -e "s|__VITE_PLATFORM_NAME__|$(esc "$VITE_PLATFORM_NAME")|g" \
+    "$f"
+done < <(find /app/dist -type f \( -name '*.js' -o -name '*.html' \) -print0)
+
+echo "Starting backend (:2892) and frontend (:3000)..."
+/app/backend &
+backend_pid=$!
+serve -s /app/dist -l 3000 &
+serve_pid=$!
+
+trap 'kill -TERM "$backend_pid" "$serve_pid" 2>/dev/null || true' TERM INT
+
+# Exit as soon as either process exits.
+wait -n