feat: Auto-detect terminal width for HUD wrapping

[seunggabi]

Problem

When the terminal is resized to a narrow width, the HUD statusline gets truncated by Claude Code with ..., cutting off useful information.

Currently, maxWidth must be manually configured in ~/.claude/settings.json. Without it, no width-aware formatting happens and the truncation is handled by Claude Code at the terminal level — meaning the user loses all content beyond the cutoff point.

Expected Behavior

The HUD should automatically detect the terminal width and wrap its output to fit — without requiring any manual configuration.

Proposed Fix

In src/hud/index.ts, after readHudConfig(), auto-detect terminal width via a fallback chain:

// Auto-detect terminal width if maxWidth not explicitly configured
if (!config.maxWidth) {
    const cols = parseInt(process.env.COLUMNS ?? '0', 10)
        || process.stderr.columns
        || process.stdout.columns
        || 0;
    if (cols > 0) {
        config.maxWidth = cols;
        if (!config.wrapMode) config.wrapMode = 'wrap';
    }
}

Why this fallback chain?

• process.env.COLUMNS — shell-exported terminal width (most common)
• process.stderr.columns — stderr is often still a TTY even when stdout is piped
• process.stdout.columns — available when stdout is a TTY

When auto-detected, wrapMode defaults to 'wrap' (instead of 'truncate') so content is preserved across multiple lines rather than being cut with ....

Impact

• Zero config change needed for users
• Existing maxWidth / wrapMode settings are fully respected (no behavior change)
• HUD becomes responsive to terminal resizing