Docker: cache deps layer for faster rebuilds (#605)

docs/platforms/hetzner.md

@@ -214,9 +214,15 @@ RUN curl -L https://github.com/steipete/wacli/releases/latest/download/wacli_Lin
 # Add more binaries below using the same pattern
 
 WORKDIR /app
-COPY . .
+COPY package.json pnpm-lock.yaml pnpm-workspace.yaml .npmrc ./
+COPY ui/package.json ./ui/package.json
+COPY patches ./patches
+COPY scripts ./scripts
+
 RUN corepack enable
 RUN pnpm install --frozen-lockfile
+
+COPY . .
 RUN pnpm build
 RUN pnpm ui:install
 RUN pnpm ui:build