refactor: eliminate duplicate code in pomodoro timer animation

[LudoLoops]

Issue

In pomodoro/pomodoro.go:70-150, the animationTicker case (lines 73-111) and secondTicker case (lines 112-148) are 99% identical.

Problem

• Massive code duplication (~80 lines of identical logic)
• Changes to animation logic require updates in 2 places
• Hard to maintain

Solution

Extract common logic:

func renderFrame(elapsed, total time.Duration, lastPrinted int) (string, int) {
    // Common rendering logic
    return bar, seconds
}

// In select:
case <-animationTicker.C:
    elapsedTime := time.Since(startTime)
    bar, seconds := renderFrame(elapsedTime, totalDuration, lastPrintedSeconds)
    if seconds != lastPrintedSeconds {
        fmt.Printf("\r%s", bar)
        lastPrintedSeconds = seconds
    }

Benefits

• Eliminates ~80 lines of code
• Easier to modify animation logic
• Single source of truth

Impact

🟢 Low - Code quality improvement