Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/@surma/rollup-plugin-off-main-thread/Dockerfile

@@ -0,0 +1,20 @@
+FROM selenium/node-chrome:latest
+
+USER root
+
+RUN apt-get update -qqy \
+  && rm -rf /var/lib/apt/lists/* /var/cache/apt/* \
+  && rm /bin/sh && ln -s /bin/bash /bin/sh \
+  && chown seluser /usr/local
+
+ENV NVM_DIR /usr/local/nvm
+RUN mkdir -p $NVM_DIR \
+  && wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.35.2/install.sh | bash \
+  && source $NVM_DIR/nvm.sh \
+  && nvm install v12
+
+ENV CHROME_BIN /opt/google/chrome/chrome
+ENV INSIDE_DOCKER=1
+
+WORKDIR /usr/src
+ENTRYPOINT source $NVM_DIR/nvm.sh && npm i && npm test