feat(bench): migrate to crossterm with colors, progress bars, and comfy-table

Complete UI overhaul with modern terminal features:

**Dependencies Added:**
- crossterm (0.28): Terminal manipulation, colors, cursor control
- serde + serde_json (1.0): Proper JSON serialization (no more manual string building!)
- comfy-table (7.1): Native table rendering with UTF-8 box drawing

**UI Improvements:**
1. **Colored Output:**
   - Green ✓ for success, Red ✗ for errors
   - Yellow table headers
   - Magenta for scaling analysis
   - Cyan for headers and labels
   - Green/Yellow highlights for fastest/slowest in summary

2. **Progress Bars:**
   - Live progress: [████░░░░] 54% (15/28) - Current template
   - Updates in place (no scrolling spam)
   - Shows current template being benchmarked

3. **Professional Tables (comfy-table):**
   - UTF-8 box-drawing characters (┌─┐│╞═╡etc.)
   - Colored headers (yellow)
   - Color-coded rows in summary (green=fastest, yellow=slowest)
   - Dynamic content arrangement

4. **Enhanced Headers:**
   - Boxed header: ╔═══ String Pipeline Throughput Benchmark ═══╗
   - Section headers with horizontal lines
   - Clear visual hierarchy

**JSON Output (serde):**
- Replaced 80+ lines of manual string concatenation
- Now uses proper Serialize derives
- Type-safe, no more concatenation errors
- Duration fields serialized as nanoseconds
- Clean, maintainable code

**Code Quality:**
- Removed artificial operation breakdown (was fake data)
- Added serialize_duration helper for consistent Duration handling
- Proper error handling with Result types
- Cleaner separation of concerns

**Modes Supported:**
- Normal: Full colored output with progress bars
- Quiet (--quiet): Minimal output, just success indicators
- JSON (--format json): Proper serde serialization to file or stdout

**Backwards Compatibility:**
- All existing CLI flags work
- JSON output structure preserved (now type-safe)
- Same benchmark logic, just better presentation

Before: Plain text with manual formatting
After: Modern terminal UI with colors, progress, and native tables ✨

Author: claude

Cargo.lock

@@ -24,6 +24,10 @@ parking_lot = "0.12.3"
 dashmap = "6.1.0"
 smallvec = "1.15.0"
 memchr = "2.7.4"
+crossterm = "0.28"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+comfy-table = "7.1"
 
 [build-dependencies]
 clap = { version = "4.5.39", features = ["derive", "cargo"] }