zsh: keep bun + pnpm PATH init, drop dead openclaw completion line

bun/pnpm/openclaw installers auto-appended to prezto-override/zshrc
(pnpm setup 2026-08-07). Keep the functional bun + pnpm blocks; the
openclaw source line targets a file that doesn't exist -- dropped.

zsh/prezto-override/zshrc

@@ -2,3 +2,18 @@ source $HOME/.zprezto/runcoms/zshrc
 
 for config_file ($HOME/.yadr/zsh/*.zsh) source $config_file
 export PATH="$HOME/.local/bin:$PATH"
+
+# bun completions
+[ -s "/home/dissimulo/.bun/_bun" ] && source "/home/dissimulo/.bun/_bun"
+
+# bun
+export BUN_INSTALL="$HOME/.bun"
+export PATH="$BUN_INSTALL/bin:$PATH"
+
+# pnpm
+export PNPM_HOME="/home/dissimulo/.local/share/pnpm"
+case ":$PATH:" in
+  *":$PNPM_HOME/bin:"*) ;;
+  *) export PATH="$PNPM_HOME/bin:$PATH" ;;
+esac
+# pnpm end