fix: update default config path to follow XDG Base Directory spec

- Change default config from ~/.gitsyncer.json to ~/.config/gitsyncer/config
- Update all documentation and help text to reflect new path
- LoadConfig still checks common locations for backward compatibility:
  - ./gitsyncer.json
  - ~/.config/gitsyncer/config (new default)
  - ~/.gitsyncer.json

This follows the XDG Base Directory specification for better organization
of configuration files.

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

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

4 files changed, 6 insertions, 5 deletions

diff --git a/internal/cli/handlers.go b/internal/cli/handlers.go
index 02df7ae..44c64c6 100644
--- a/internal/cli/handlers.go
+++ b/internal/cli/handlers.go
@@ -69,7 +69,7 @@ func findDefaultConfigPath() string {
 	// Check common config locations
 	configLocations := []string{
 		filepath.Join(".", "gitsyncer.json"),
-		filepath.Join(home, ".config", "gitsyncer", "config.json"),
+		filepath.Join(home, ".config", "gitsyncer", "config"),
 		filepath.Join(home, ".gitsyncer.json"),
 	}
 
@@ -88,7 +88,7 @@ func ShowConfigHelp() {
 	
 	fmt.Println("No configuration file found. Please create one of:")
 	fmt.Printf("  - ./gitsyncer.json\n")
-	fmt.Printf("  - %s/.config/gitsyncer/config.json\n", home)
+	fmt.Printf("  - %s/.config/gitsyncer/config\n", home)
 	fmt.Printf("  - %s/.gitsyncer.json\n", home)
 	fmt.Println("\nOr specify a config file with --config flag")
 	fmt.Println("\nExample configuration:")
diff --git a/internal/cmd/root.go b/internal/cmd/root.go
index 04ea6dd..927a9b8 100644
--- a/internal/cmd/root.go
+++ b/internal/cmd/root.go
@@ -53,7 +53,7 @@ func Execute() {
 
 func init() {
 	// Global flags
-	rootCmd.PersistentFlags().StringVarP(&cfgFile, "config", "c", "", "configuration file (default: ~/.gitsyncer.json)")
+	rootCmd.PersistentFlags().StringVarP(&cfgFile, "config", "c", "", "configuration file (default: ~/.config/gitsyncer/config)")
 	
 	// Set default work directory
 	home, err := os.UserHomeDir()
diff --git a/internal/cmd/test.go b/internal/cmd/test.go
index 0590719..2c50112 100644
--- a/internal/cmd/test.go
+++ b/internal/cmd/test.go
@@ -44,7 +44,7 @@ var testConfigCmd = &cobra.Command{
   gitsyncer test config
   
   # Test specific config file
-  gitsyncer test config -c ~/my-gitsyncer.json`,
+  gitsyncer test config -c ~/my-config.json`,
 	Run: func(cmd *cobra.Command, args []string) {
 		// Try to load and validate config
 		cfg, err := config.Load(cfgFile)
diff --git a/internal/config/config.go b/internal/config/config.go
index 799c792..a141c81 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -34,7 +34,8 @@ func Load(path string) (*Config, error) {
 		if err != nil {
 			return nil, fmt.Errorf("failed to get home directory: %w", err)
 		}
-		path = filepath.Join(home, ".gitsyncer.json")
+		// Use XDG config directory
+		path = filepath.Join(home, ".config", "gitsyncer", "config")
 	} else if len(path) >= 2 && path[:2] == "~/" {
 		// Expand home directory if needed
 		home, err := os.UserHomeDir()