fix: Docker build — install tailwindcss in /tmp to avoid Deno conflict

npm install in /app conflicts with Deno's node_modules/.deno structure.
Install tailwindcss + CLI in /tmp and invoke the binary directly,
bypassing both npx and the conflicting node_modules.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: motxx

Dockerfile

@@ -31,8 +31,16 @@ RUN deno install
 
 COPY . .
 
-# Build frontend (tailwindcss needed for @import "tailwindcss" in CSS)
-RUN npm install tailwindcss @tailwindcss/cli && deno task build:ui && deno task build:css
+# Build frontend
+RUN deno task build:ui
+# Tailwind CSS v4: @import "tailwindcss" needs the package resolvable.
+# Install in /tmp to avoid conflicts with Deno's node_modules, then
+# run the CLI directly.
+RUN cd /tmp && npm init -y -q && npm install -q tailwindcss @tailwindcss/cli 2>/dev/null \
+  && /tmp/node_modules/.bin/tailwindcss -i /app/src/ui/globals.css -o /app/dist/ui/generated.css \
+  && /tmp/node_modules/.bin/tailwindcss -i /app/src/ui/requester/globals.css -o /app/dist/ui/requester/generated.css \
+  && /tmp/node_modules/.bin/tailwindcss -i /app/src/ui/dashboard/globals.css -o /app/dist/ui/dashboard/generated.css \
+  && rm -rf /tmp/node_modules /tmp/package.json /tmp/package-lock.json
 
 ENV NODE_ENV=production
 ENV REFERENCE_APP_PORT=8080