refactor: add bytecode format module for shared formatting

[zharinov]

Summary

• Add format module to bytecode with shared formatting utilities
• Provides column layout constants, symbol formatting, and line building
• Will be used by dump and trace for consistent output formatting

Contents

• Symbol struct for 5-char navigation/status symbols (▽, ▷, △, ●, ○, etc.)
• nav_symbol() / nav_symbol_epsilon() for navigation display
• cols module with column width constants
• trace module with trace-specific symbols
• LineBuilder for consistent line formatting
• format_effect() for effect operation display
• Utility functions: width_for_count, truncate_text, superscript

Test plan

• cargo check passes
• Module tests pass