fix: use docker compose watch under dev

frontend/Dockerfile

@@ -1,10 +1,9 @@
-# Stage 0, "build-stage", based on Bun, to build and compile the frontend
-FROM oven/bun:1 AS build-stage
+# Shared Bun stage for frontend dependencies and sources
+FROM oven/bun:1 AS bun-base
 
 WORKDIR /app
 
 COPY package.json bun.lock /app/
-
 COPY frontend/package.json /app/frontend/
 
 WORKDIR /app/frontend
@@ -14,10 +13,22 @@ RUN bun install
 COPY ./frontend /app/frontend
 ARG VITE_API_URL
 
+
+# Development stage for docker compose watch + Vite HMR
+FROM bun-base AS dev-stage
+
+EXPOSE 80
+
+CMD ["bun", "run", "dev", "--host", "0.0.0.0", "--port", "80"]
+
+
+# Build stage for production assets
+FROM bun-base AS build-stage
+
 RUN bun run build
 
 
-# Stage 1, based on Nginx, to have only the compiled app, ready for production with Nginx
+# Production stage serving compiled assets with Nginx
 FROM nginx:1
 
 COPY --from=build-stage /app/frontend/dist/ /usr/share/nginx/html