fix(docker): set www-data uid/gid to 1000 to match host user on bind mounts

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

docker/app/Dockerfile

@@ -12,6 +12,8 @@ RUN curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
     && apt-get install -y nodejs \
     && apt-get clean && rm -rf /var/lib/apt/lists/*
 
+RUN usermod -u 1000 www-data && groupmod -g 1000 www-data
+
 WORKDIR /var/www/html
 COPY . .
 RUN composer install --no-dev --optimize-autoloader \