fix(ocp-connect): write ~/.zshrc on macOS (default shell since Catalina)

macOS default shell has been zsh since Catalina (2019). The previous
rc-file selection logic treated macOS the same as Linux, so on a fresh
Mac where ~/.zshrc did not already exist AND the script was invoked via
`bash -s --` (e.g. `curl | bash`), the $SHELL guard was `/bin/bash`
and neither condition for zshrc was true — resulting in only ~/.bashrc
being written. Since ~/.bashrc is not sourced by interactive zsh
sessions, the OPENAI_BASE_URL / OPENAI_API_KEY exports were invisible
to interactive shells.

Fix:
- Add an explicit `elif $is_mac` branch that unconditionally includes
  ~/.zshrc: create the file (empty) if it does not yet exist, since
  zsh tolerates an empty ~/.zshrc.
- On macOS, ~/.bashrc is only written if it already exists — consistent
  with the task spec ("don't create ~/.bashrc if it didn't exist").
- Linux path is preserved unchanged.
- Fix the "Reload your shell" hint at script end: previously it printed
  only the last loop variable `$rc_file` (stale reference outside the
  loop). Now it iterates `${rc_files[@]}` so both files are shown on
  macOS (reproducing the Round A bug: hint said only `source ~/.bashrc`
  even when zshrc should also be reloaded).

Smoke-tested with HOME=/tmp/fakehome redirect for three scenarios:
  1. Fresh MacBook (no .bashrc, no .zshrc)  → only .zshrc created+written
  2. macOS with existing .bashrc             → both .bashrc and .zshrc written
  3. Linux with bash, no .bashrc             → .bashrc written (unchanged)

Identified during Round A testing on MacBook 2026-05-08.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ocp-connect

@@ -582,11 +582,19 @@ print(k if k else '')
   if [[ "${SHELL:-}" == */fish ]]; then
     echo "  Note: fish shell detected. Writing to ~/.bashrc — add to fish config manually."
     rc_files+=("$HOME/.bashrc")
+  elif $is_mac; then
+    # macOS: default shell since Catalina (2019) is zsh.
+    # Always write ~/.zshrc (create if absent — zsh tolerates an empty file).
+    # Only write ~/.bashrc if it already exists (don't surprise users with new files).
+    [[ -f "$HOME/.bashrc" ]] && rc_files+=("$HOME/.bashrc")
+    # zshrc: always include on macOS; create the file if it doesn't exist yet
+    [[ -f "$HOME/.zshrc" ]] || touch "$HOME/.zshrc"
+    rc_files+=("$HOME/.zshrc")
   else
-    # Always write both on macOS (default shell is zsh but some tools source bashrc)
+    # Linux / other: write to whichever rc files already exist or match current shell
     [[ -f "$HOME/.bashrc" || "${SHELL:-}" == */bash ]] && rc_files+=("$HOME/.bashrc")
     [[ -f "$HOME/.zshrc" || "${SHELL:-}" == */zsh ]] && rc_files+=("$HOME/.zshrc")
-    # If neither exists, create for current shell
+    # If neither exists, fall back to creating one for the current shell
     [[ ${#rc_files[@]} -eq 0 ]] && rc_files+=("$HOME/.${SHELL##*/}rc")
   fi
 
@@ -705,7 +713,9 @@ PYEOF
 
   echo ""
   echo "  Done. Reload your shell to apply:"
-  echo "    source $rc_file"
+  for rc_file in "${rc_files[@]}"; do
+    echo "    source $rc_file"
+  done
 }
 
 main "$@"