feat: add shared shell utilities

- Add common aliases, exports, and functions
- Add shell completions and prompt configuration
- Add sync utilities for cross-shell compatibility

🤖 Generated with [Claude Code](https://claude.ai/code)

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

shared/completions

@@ -0,0 +1,83 @@
+# Shared Completion Functions
+# Compatible with both bash and zsh
+
+# Custom completion for 'ta' command
+_ta_complete() {
+  local cur prev actions layers tf_cmds ansible_cmds
+  
+  # Get current word and previous word based on shell
+  if [[ -n "$ZSH_VERSION" ]]; then
+    # Zsh completion
+    cur="${words[CURRENT]}"
+    prev="${words[CURRENT-1]}"
+    local comp_word=$CURRENT
+  else
+    # Bash completion
+    local cur prev
+    _get_comp_words_by_ref cur prev
+    local comp_word=$COMP_CWORD
+  fi
+  
+  actions="terraform ansible install remove"
+  layers="foundation showcase"
+  tf_cmds="init plan apply refresh destroy"
+  ansible_cmds=""  # Add Ansible-specific commands here if needed
+
+  case $comp_word in
+    1)
+      if [[ -n "$ZSH_VERSION" ]]; then
+        compadd $actions
+      else
+        COMPREPLY=( $(compgen -W "$actions" -- "$cur") )
+      fi
+      ;;
+    2)
+      if [[ "$prev" == "terraform" || "$prev" == "ansible" ]]; then
+        if [[ -n "$ZSH_VERSION" ]]; then
+          compadd $layers
+        else
+          COMPREPLY=( $(compgen -W "$layers" -- "$cur") )
+        fi
+      fi
+      ;;
+    3)
+      if [[ -n "$ZSH_VERSION" ]]; then
+        local first_word="${words[2]}"
+      else
+        local first_word="${COMP_WORDS[1]}"
+      fi
+      
+      if [[ "$first_word" == "terraform" ]]; then
+        if [[ -n "$ZSH_VERSION" ]]; then
+          compadd $tf_cmds
+        else
+          COMPREPLY=( $(compgen -W "$tf_cmds" -- "$cur") )
+        fi
+      elif [[ "$first_word" == "ansible" ]]; then
+        if [[ -n "$ZSH_VERSION" ]]; then
+          compadd $ansible_cmds
+        else
+          COMPREPLY=( $(compgen -W "$ansible_cmds" -- "$cur") )
+        fi
+      fi
+      ;;
+    *)
+      # Fallback to file completions
+      if [[ -n "$ZSH_VERSION" ]]; then
+        _files
+      else
+        COMPREPLY=( $(compgen -f -- "$cur") )
+      fi
+      ;;
+  esac
+  return 0
+}
+
+# Register completion based on shell
+if [[ -n "$ZSH_VERSION" ]]; then
+  # Zsh completion registration
+  compdef _ta_complete ta
+else
+  # Bash completion registration
+  complete -F _ta_complete ta
+fi