style(tools): unify console output with [I/W/E] [Module] color-coded format

- Add ANSI color coding: [I]=green, [W]=yellow, [E]=red
- Format: [Level] [Module] message with 4-char indent for data rows
- Error detail lines use |-> tree connector
- Remove extra blank lines between outputs (except list)
- Modules: CLI, Preview, Builder, Server, Watcher

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/cli/list.go

@@ -37,7 +37,7 @@ func runList(c *cli.Context) error {
 	}
 
 	absDir, _ := filepath.Abs(folder)
-	fmt.Printf("Available styles in '%s' (%d):\n", filepath.Base(absDir), len(themes))
+	fmt.Printf("\033[32m[I]\033[0m [Preview] Available styles in '%s' (%d):\n", filepath.Base(absDir), len(themes))
 
 	sort.Strings(themes)
 	for _, t := range themes {
@@ -51,7 +51,7 @@ func runList(c *cli.Context) error {
 			}
 			return nil
 		})
-		fmt.Printf("  %-16s (%d .tmpl files)\n", t, count)
+		fmt.Printf("\033[32m[I]\033[0m [Preview]    %-16s (%d .tmpl files)\n", t, count)
 	}
 	return nil
 }