Fix problem where container home was seperate for each project dir

The problem was that we mounted `pwd` as HOME and that meant that
every time git was used it would look into the data and work for a
long time, and it would also commit everything there.

Now we have a central container-home directory in the directory
where we checked out this git repo and it is used by each session
independent of in which project directory we are.

Dockerfile

@@ -1,31 +1,31 @@
 FROM archlinux:latest
 
-# Build args for user
 ARG USERNAME=dev
 ARG UID=1000
 ARG GID=1000
 
-# Install basic tools
 RUN pacman -Syu --noconfirm \
+        base-devel \
         git \
         ca-certificates \
-        curl \
         bash \
-    && pacman -Scc --noconfirm
+        less \
+        ripgrep && \
+    groupadd -g ${GID} ${USERNAME} && \
+    useradd -m -u ${UID} -g ${GID} -s /bin/bash ${USERNAME} && \
+    pacman -Scc --noconfirm
 
-# Create user
-RUN groupadd -g ${GID} ${USERNAME} && \
-    useradd -m -u ${UID} -g ${GID} -s /bin/bash ${USERNAME}
+WORKDIR /tmp
+USER ${USERNAME}
+
+RUN git clone https://aur.archlinux.org/opencode-bin.git && \
+    cd opencode-bin && \
+    makepkg --noconfirm
+
+USER root
+RUN pacman -U --noconfirm /tmp/opencode-bin/*.pkg.tar.zst && \
+    rm -rf /tmp/opencode-bin && \
+    pacman -Scc --noconfirm
 
-# Switch to non-root user
 USER ${USERNAME}
 WORKDIR /home/${USERNAME}
-
-# Install OpenCode CLI via official installer
-RUN curl -fsSL https://opencode.ai/install | bash
-
-# Add OpenCode CLI to PATH
-ENV PATH="/home/${USERNAME}/.opencode/bin:${PATH}"
-
-# Default working directory
-WORKDIR /home/${USERNAME}