Set personal git identity, fix zshrc theme, improve bw-ssh service

- config/git/gitconfig: real name, email, and SSH signing key
- config/shell/zshrc: fix typo 'powerlevel10zsh' → 'powerlevel10k'
- config/systemd/bw-ssh-keys.service: depend on graphical-session
  instead of network (ssh-agent starts with session); add explicit
  PATH so bw and jq are found; add RemainAfterExit=yes
  (avoids restart loop on oneshot services)

config/shell/zshrc

@@ -24,7 +24,7 @@ export PATH=$HOME/bin:$HOME/.local/bin:/usr/local/bin:$PATH
 
 # ---- Oh My Zsh ----
 export ZSH="$HOME/.oh-my-zsh"
-ZSH_THEME="powerlevel10k/powerlevel10zsh"
+ZSH_THEME="powerlevel10k/powerlevel10k"
 
 # ---- Plugins ----
 plugins=(git zsh-autosuggestions)