feat(daemon): zsh OSC 133 shell integration via per-surface ZDOTDIR

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/spaceshd/src/shell_integration/spacesh.zsh

@@ -0,0 +1,16 @@
+# spacesh zsh OSC 133 integration. Sourced from a per-surface ZDOTDIR .zshrc
+# after the user's ~/.zshrc. Emits semantic-prompt markers so the daemon can
+# detect command start/end and exit status.
+autoload -Uz add-zsh-hook 2>/dev/null
+
+_spacesh_precmd() {
+  local code=$?
+  # End previous command (D) with its exit code, then mark prompt start (A).
+  print -n "\e]133;D;${code}\a\e]133;A\a"
+}
+_spacesh_preexec() {
+  # Command output begins (C).
+  print -n "\e]133;C\a"
+}
+add-zsh-hook precmd _spacesh_precmd 2>/dev/null
+add-zsh-hook preexec _spacesh_preexec 2>/dev/null