fix: Add nano and vim editors to devcontainer with default editor config

Fixes #2098

- Add nano and vim to provide editor choices for users
- Set EDITOR and VISUAL environment variables to nano as default
- This ensures /memory command and other tools work out of the box

Users can still change their preferred editor by setting these environment variables in their shell configuration.

.devcontainer/Dockerfile

@@ -19,7 +19,9 @@ RUN apt update && apt install -y less \
   iproute2 \
   dnsutils \
   aggregate \
-  jq
+  jq \
+  nano \
+  vim
 
 # Ensure default node user has access to /usr/local/share
 RUN mkdir -p /usr/local/share/npm-global && \
@@ -57,6 +59,10 @@ ENV PATH=$PATH:/usr/local/share/npm-global/bin
 # Set the default shell to zsh rather than sh
 ENV SHELL=/bin/zsh
 
+# Set the default editor and visual
+ENV EDITOR nano
+ENV VISUAL nano
+
 # Default powerline10k theme
 RUN sh -c "$(wget -O- https://github.com/deluan/zsh-in-docker/releases/download/v1.2.0/zsh-in-docker.sh)" -- \
   -p git \