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/sync

@@ -0,0 +1,84 @@
+# Dotfiles Auto-Sync Configuration
+# This file is sourced by shell configurations to enable automatic syncing
+
+# Function to run dotfiles sync
+dotfiles_sync() {
+    if [[ -x "$HOME/.dotfiles/sync.sh" ]]; then
+        "$HOME/.dotfiles/sync.sh" --background
+    fi
+}
+
+# Function to enable/disable sync
+dotfiles_sync_enable() {
+    echo "true" > "$HOME/.dotfiles/.sync_enabled"
+    echo "✅ Dotfiles auto-sync enabled"
+}
+
+dotfiles_sync_disable() {
+    echo "false" > "$HOME/.dotfiles/.sync_enabled"
+    echo "❌ Dotfiles auto-sync disabled"
+}
+
+# Function to manually trigger sync
+dotfiles_sync_now() {
+    if [[ -x "$HOME/.dotfiles/sync.sh" ]]; then
+        "$HOME/.dotfiles/sync.sh" --manual
+    else
+        echo "❌ Sync script not found or not executable"
+    fi
+}
+
+# Function to force sync (ignores timing)
+dotfiles_sync_force() {
+    if [[ -x "$HOME/.dotfiles/sync.sh" ]]; then
+        "$HOME/.dotfiles/sync.sh" --force
+    else
+        echo "❌ Sync script not found or not executable"
+    fi
+}
+
+# Function to show sync status
+dotfiles_sync_status() {
+    local sync_enabled_file="$HOME/.dotfiles/.sync_enabled"
+    local last_sync_file="$HOME/.dotfiles/.last_sync"
+    local sync_log="$HOME/.dotfiles/.sync.log"
+    
+    echo "🔧 Dotfiles Sync Status:"
+    
+    if [[ -f "$sync_enabled_file" ]]; then
+        local enabled=$(cat "$sync_enabled_file")
+        if [[ "$enabled" == "true" ]]; then
+            echo "   Status: ✅ Enabled"
+        else
+            echo "   Status: ❌ Disabled"
+        fi
+    else
+        echo "   Status: ✅ Enabled (default)"
+    fi
+    
+    if [[ -f "$last_sync_file" ]]; then
+        local last_sync=$(cat "$last_sync_file")
+        local last_sync_date=$(date -d "@$last_sync" 2>/dev/null || echo "Unknown")
+        echo "   Last sync: $last_sync_date"
+    else
+        echo "   Last sync: Never"
+    fi
+    
+    if [[ -f "$sync_log" ]]; then
+        echo "   Recent activity:"
+        tail -3 "$sync_log" | sed 's/^/     /'
+    fi
+}
+
+# Auto-sync on shell startup (only for interactive shells)
+if [[ $- == *i* ]] && [[ -n "$HOME" ]] && [[ -d "$HOME/.dotfiles" ]]; then
+    dotfiles_sync
+    
+    # Also check for updates periodically (background, no output)
+    if [[ -f "$HOME/.dotfiles/lib/update_checker.sh" ]]; then
+        (
+            source "$HOME/.dotfiles/lib/update_checker.sh"
+            check_for_updates false false >/dev/null 2>&1 &
+        )
+    fi
+fi