fix(fireshare): rebuild client on update to fix nginx 500

After update, the frontend was not rebuilt while nginx still served /opt/fireshare/app/client/build, causing 500 errors. Match install behavior with npm install and npm run build.

Fixes #14812

Co-authored-by: Cursor <cursoragent@cursor.com>

ct/fireshare.sh

@@ -53,6 +53,12 @@ function update_script() {
     export VIDEO_DIRECTORY=/opt/fireshare-videos
     export PROCESSED_DIRECTORY=/opt/fireshare-processed
     $STD uv run flask db upgrade
+
+    msg_info "Building Fireshare Client"
+    cd /opt/fireshare/app/client
+    $STD npm install
+    $STD npm run build
+    msg_ok "Built Fireshare Client"
     msg_ok "Updated Fireshare"
 
     msg_info "Starting Service"