feat(ui): replace Tailwind CSS CDN with compiled v3 production build

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/85d2244d-170a-48d3-8f6b-b4c124a49ed9

Dockerfile

@@ -27,7 +27,20 @@ RUN pip install --no-cache-dir -r requirements.txt \
     && find /opt/venv -type f -name "*.pyc" -delete \
     && find /opt/venv -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true
 
-# ── Stage 2: Documentation builder ──────────────────────────────────────────
+# ── Stage 2: Frontend asset builder (Tailwind CSS) ──────────────────────────
+FROM node:20-alpine AS frontend-builder
+
+WORKDIR /frontend
+
+# Install dependencies first (layer-cached unless package.json/lockfile changes)
+COPY frontend/package.json frontend/package-lock.json ./
+RUN npm ci --omit=dev
+
+# Copy source files and compile Tailwind CSS
+COPY frontend/ ./
+RUN npm run build
+
+# ── Stage 3: Documentation builder ──────────────────────────────────────────
 FROM python:3.14.3-slim AS docs-builder
 
 WORKDIR /docs
@@ -43,7 +56,7 @@ COPY mkdocs.yml /docs/mkdocs.yml
 # Build the static documentation site
 RUN mkdocs build --config-file /docs/mkdocs.yml --site-dir /docs/docs_build
 
-# ── Stage 3: Runtime image ───────────────────────────────────────────────────
+# ── Stage 4: Runtime image ───────────────────────────────────────────────────
 FROM python:3.14.3-slim
 
 WORKDIR /app
@@ -68,6 +81,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 # Copy application code
 COPY ./app /app/app
 COPY ./frontend /app/frontend
+# Overlay compiled Tailwind CSS from the frontend build stage
+COPY --from=frontend-builder /frontend/static/styles.css /app/frontend/static/styles.css
 COPY ./migrations /app/migrations
 COPY ./alembic.ini /app/alembic.ini
 COPY ./LICENSE /app/LICENSE