Change base docker image with more stuff preinstalled

Dockerfile

@@ -1,25 +1,18 @@
-# Start with the official Cachix Devenv image (which has Nix and Devenv pre-installed)
-FROM ghcr.io/cachix/devenv/devenv:latest
+# Start with a official gitea runner image based on ubuntu with node installed
+FROM docker.gitea.com/runner-images:ubuntu-latest-slim
 
-# Switch to root to install system-level packages
-USER root
+# Install Nix as a multi-user installation
+RUN curl -L https://nixos.org/nix/install | sh -s -- --daemon
+ENV PATH="/nix/var/nix/profiles/default/bin:$PATH"
 
-# Install the critical dependencies for Gitea Actions
-# - nodejs: Required to run standard actions (like actions/checkout)
-# - sudo: Required by many actions to escalate privileges
-# - bash & jq: Standard utilities often expected in CI scripts
-RUN apt-get update && \
-    apt-get install -y nodejs sudo bash jq && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
+# Enable flakes and nix-command
+RUN mkdir -p /etc/nix && \
+    echo "experimental-features = nix-command flakes" >> /etc/nix/nix.conf
 
-# Allow passwordless sudo for any user in the container.
-# CI runners often execute as 'runner' or 'root'. This guarantees neither gets stuck.
-RUN echo "ALL ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
+# Install devenv (the Nix way, not the apt-get way)
+RUN nix profile install nixpkgs#devenv
 
-# Guarantee the image ships without the Nix sandboxing artifact.
-# This prevents the "purity" crash on the very first Nix run.
+# Cleanup, otherwise nix panicks
 RUN rm -rf /homeless-shelter
 
-# Set the default shell to bash
 CMD ["/bin/bash"]