fix(cicd): fix yarn version, surface the real failure, bust cache

Dockerfile

@@ -1,27 +1,22 @@
 # Build stage
 FROM node:20-alpine AS builder
 WORKDIR /app
-# Enable Corepack so we can use Yarn v4
-RUN corepack enable && corepack prepare yarn@stable --activate
+# Enable Corepack so we can use Yarn v4 (pinned to match lockfile)
+RUN corepack enable && corepack prepare yarn@4.11.0 --activate
 # Force Yarn to use node_modules instead of PnP
 ENV YARN_NODE_LINKER=node-modules
 COPY package.json yarn.lock ./
 RUN yarn install --immutable
 COPY . .
-RUN yarn build
+RUN yarn build && ls -la dist
 
 # Production stage - Caddy
 FROM caddy:2-alpine
-
 WORKDIR /usr/share/caddy
-
 # Copy built static files from the builder stage
 COPY --from=builder /app/dist .
-
 # Copy our local Caddyfile config
 COPY Caddyfile /etc/caddy/Caddyfile
-
 EXPOSE 3000
-
 # Start caddy using the config file
 CMD ["caddy", "run", "--config", "/etc/caddy/Caddyfile", "--adapter", "caddyfile"]