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/prompt

@@ -0,0 +1,25 @@
+# Shared Prompt Configuration
+# Set up a consistent prompt across shells
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[0;33m'
+BLUE='\033[0;34m'
+PURPLE='\033[0;35m'
+CYAN='\033[0;36m'
+WHITE='\033[0;37m'
+RESET='\033[0m'
+
+# Git branch display function
+git_branch() {
+    git branch 2>/dev/null | grep '^*' | colrm 1 2
+}
+
+# Git status indicators
+git_status() {
+    local status=$(git status --porcelain 2>/dev/null)
+    if [[ -n $status ]]; then
+        echo "*"
+    fi
+}