fix: fallback to npm install when lockfile missing (#6)

package-lock.json is .gitignored so npm ci fails in Coolify build.
Use npm install as fallback when lockfile not present.

Dockerfile

@@ -4,7 +4,8 @@ FROM node:22-alpine AS builder
 WORKDIR /app
 
 COPY package.json package-lock.json* ./
-RUN --mount=type=cache,target=/root/.npm npm ci
+RUN --mount=type=cache,target=/root/.npm \
+    if [ -f package-lock.json ]; then npm ci; else npm install --no-audit --no-fund; fi
 
 COPY . .
 RUN npm run build