Extract Vue frontend into separate container and add stp_wasm crate

Move Vue app from nginx/vue/ to top-level vue/ with its own Dockerfile,
update docker-compose configs and nginx proxy to serve from the new
container, and add initial Rust WASM crate (stp_wasm). Also fix .gitignore
to exclude Rust target/ directories.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nginx/Dockerfile

@@ -1,21 +1,9 @@
-# Stage 1: Build Vue app
-FROM node:22-slim AS build
-RUN apt-get update && apt-get install -y make git && rm -rf /var/lib/apt/lists/*
-WORKDIR /app
-COPY vue/package.json vue/package-lock.json ./
-RUN npm ci
-COPY vue/ ./
-RUN npm run build
-
-# Stage 2: Serve with nginx
 FROM nginx:latest
 RUN rm -rf /etc/nginx/html/* && \
     apt-get update && apt-get install -y gettext-base && \
     rm -rf /var/lib/apt/lists/*
-COPY --from=build /app/dist /etc/nginx/html/
 COPY nginx.conf.template /etc/nginx/nginx.conf.template
 COPY nginx_setup.conf.template /etc/nginx/nginx_setup.conf.template
 COPY nginx_dev.conf.template /etc/nginx/nginx_dev.conf.template
-COPY robots.txt /etc/nginx/html/robots.txt
 COPY entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]