Fix pnpm installation and build process

Dockerfile

@@ -5,14 +5,17 @@ MAINTAINER Cloudron Support <support@cloudron.io>
 # Install Node.js 20 and pnpm
 RUN curl -fsSL https://deb.nodesource.com/setup_20.x | bash - && \
     apt-get install -y nodejs && \
-    npm install -g pnpm@latest
+    npm install -g pnpm@9.12.4
 
 # Set up application directory
 WORKDIR /app/code
 
 # Clone and build Docmost
 RUN git clone https://github.com/docmost/docmost.git . && \
-    pnpm install && \
+    rm -rf .git && \
+    corepack enable && \
+    corepack prepare pnpm@latest --activate && \
+    pnpm install --frozen-lockfile && \
     pnpm build
 
 # Create necessary directories