feat: add ASCII art email signature and update documentation

- Add signature.txt with stylish VALKNAR banner and contact info
- Update README.md to document the new signature file
- Clean up .gitignore to track signature.txt
- Remove legacy config files (prettier, rubocop, pre-commit, etc.)
- Update arty.yml with additional installation scripts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

arty.yml

@@ -1,8 +1,8 @@
 name: "Valknar's home"
-version: '1.0.0'
+version: "1.0.0"
 description: "Valknar's home repository"
-author: 'valknar@pivoine.art'
-license: 'MIT'
+author: "valknar@pivoine.art"
+license: "MIT"
 
 references:
   - url: git@github.com:valknarogg/bin.git
@@ -29,16 +29,26 @@ references:
 scripts:
   debian/install:
     sudo apt install curl zsh fzf davfs2 krusader make imagemagick ffmpeg yt-dlp
+    thunderbird
   rust/install: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+  node/install: nvm install
+  ruby/install: rbenv install
+  python/install: pyenv/install
   zed/install: curl -f https://zed.dev/install.sh | sh
   claude/install: curl -fsSL https://claude.ai/install.sh | bash
   mattermost/install:
     curl -fsS -o- https://deb.packages.mattermost.com/setup-repo.sh | sudo bash
     && sudo apt install mattermost-desktop
-  joplin/install:
-    wget -O -
+  joplin/install: wget -O -
     https://raw.githubusercontent.com/laurent22/joplin/dev/Joplin_install_and_update.sh
     \ | bash
   yq/install:
     wget https://github.com/mikefarah/yq/releases/latest/download/yq_linux_amd64
     -O /usr/local/bin/yq &&\ chmod +x /usr/local/bin/yq
+  spotify/install:
+    curl -sS https://download.spotify.com/debian/pubkey_C85668DF69375001.gpg |
+    sudo gpg --dearmor --yes -o /etc/apt/trusted.gpg.d/spotify.gpg && echo "deb
+    https://repository.spotify.com stable non-free" | sudo tee
+    /etc/apt/sources.list.d/spotify.list && sudo apt-get update && sudo apt-get
+    install spotify-client
+  npm/install: npm i -g npm pnpm @valknarthing/llmx