prevent permission errors on bash_profile/rc/zshrc (#96)

We recently had an issue where bash_profile/rc/zshrc were already
created by the root user, and it was causing permission issues in the
install script:

![image](https://github.com/ConsultingMD/homebrew-ih-public/assets/67805647/0dd9d18c-cad1-47ef-803b-00a28a7da00a)

This PR adds checks and will fix the permissions if they're incorrect.

VERSION

@@ -1 +1 @@
-0.1.55
+0.1.56

formula/ih-core.rb

@@ -1,5 +1,5 @@
 class IhCore < Formula
-  VERSION="0.1.55"
+  VERSION="0.1.56"
   desc "Brew formula for installing core tools used at Included Health engineering."
   homepage "https://github.com/ConsultingMD/homebrew-ih-public"
   license "CC BY-NC-ND 4.0"

lib/core/shell/step.sh

@@ -104,6 +104,18 @@ function ih::setup::core.shell::install() {
   export IH_WANT_RE_SOURCE=1
 }
 
+function ih::setup::core.shell::private::ensure_correct_ownership() {
+  local file="$1"
+  if [[ -e "$file" ]]; then
+    local current_owner
+    current_owner=$(stat -f '%Su' "$file") # For macOS
+    if [[ "$current_owner" != "$(whoami)" ]]; then
+      echo "Changing ownership of $file to the current user..."
+      sudo chown "$(whoami)" "$file"
+    fi
+  fi
+}
+
 # shellcheck disable=SC2016
 BOOTSTRAP_SOURCE_LINE='
 # This loads the Included Health shell augmentations into your interactive shell
@@ -118,6 +130,10 @@ function ih::setup::core.shell::private::configure-bash() {
     touch ~/.bashrc
   fi
 
+  # prevent permission errors from files accidentally created as root
+  ih::setup::core.shell::private::ensure_correct_ownership ~/.bash_profile
+  ih::setup::core.shell::private::ensure_correct_ownership ~/.bashrc
+
   # Check if .bash_profile exists and if it doesn't already source .bashrc, then add it
   if [[ ! -e ~/.bash_profile ]] || ! grep -q "source ~/.bashrc" ~/.bash_profile; then
     echo "Ensuring .bash_profile sources .bashrc..."
@@ -147,6 +163,9 @@ function ih::setup::core.shell::private::configure-zshrc() {
     touch "${HOME}/.zshrc"
   fi
 
+  # prevent permission errors from files accidentally created as root
+  ih::setup::core.shell::private::ensure_correct_ownership ~/.zshrc
+
   # apply fix to support brew completions in zsh: https://docs.brew.sh/Shell-Completion#configuring-completions-in-zsh
   chmod -R go-w "$(brew --prefix)/share"