fix(bench): correct header box alignment with unicode-aware width calculation

Fixed the alignment offset in print_header() function:
- Changed padding calculation from (110 - text.len()) to (107 - text_width)
- Added unicode_width dependency for proper emoji display width handling
- Now correctly handles headers with emojis like "📊 SUMMARY"

The box structure is:
- Total width: 110 chars
- Border + space: ║ (2 chars)
- Text content: text_width chars
- Padding: (107 - text_width) chars
- Final border: ║ (1 char)

Author: claude

Cargo.lock

@@ -28,6 +28,7 @@ crossterm = "0.28"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 comfy-table = "7.1"
+unicode-width = "0.2"
 
 [build-dependencies]
 clap = { version = "4.5.39", features = ["derive", "cargo"] }

Cargo.toml

@@ -12,6 +12,7 @@ use serde::{Serialize, Serializer};
 use std::io::{self, Write};
 use std::time::{Duration, Instant};
 use string_pipeline::Template;
+use unicode_width::UnicodeWidthStr;
 
 // Helper to serialize Duration as nanoseconds
 fn serialize_duration<S>(duration: &Duration, serializer: S) -> Result<S::Ok, S::Error>
@@ -392,6 +393,7 @@ fn format_size(size: usize) -> String {
 // Styled output helpers
 fn print_header(text: &str) {
     let mut stdout = io::stdout();
+    let text_width = text.width();
     let _ = execute!(
         stdout,
         SetForegroundColor(Color::Cyan),
@@ -400,7 +402,7 @@ fn print_header(text: &str) {
         Print("═".repeat(108)),
         Print("╗\n║ "),
         Print(text),
-        Print(" ".repeat(110 - text.len())),
+        Print(" ".repeat(107 - text_width)),
         Print("║\n╚"),
         Print("═".repeat(108)),
         Print("╝\n"),