Optimize TerminalCommandDisplay visual wrapping with early-exit preview - #1224

Nice motivation and benchmarking — early-exiting the wrap loop once maxLines is reached is the right idea for terminal-command-display.tsx, and the OpenTUI render tests are a welcome addition since this component previously had none.

However, there's a real correctness bug in the collapsed-state loop:

if (line.length === 0) {
  linesProcessed++
  continue
}

This skips blank lines entirely instead of treating them as one visual line (as getLastNVisualLines did originally). Any command output with interstitial blank lines (build logs, test summaries, git log --stat, etc.) will render a preview missing those blank lines — a visible layout change, not just a perf win. The same skip happens in the remainingVisualLines estimate and the isExpanded totalVisual calc, so hiddenLinesCount/hasMoreLines will also be off whenever blank lines are present. None of the three new tests exercise output with blank lines, so this slipped through despite the '100% exact parity' claim in the PR body.

Separately, the off-screen line-count estimate (Math.ceil(line.length / width)) is a character-count approximation of what the regex-based word wrapper actually produces. That's a reasonable perf trade-off for a hidden-line counter, but it means the 'Show N more lines' label can now be wrong by a line or two versus the real wrap result — worth calling out explicitly as an approximation rather than presenting it as parity-preserving.

Fix the blank-line handling (count it as one line, don't skip it) and either compute the hidden count from the real wrapper for the first chunk past maxLines or document the approximation, and this becomes a solid port candidate.

Thanks for catching this @codebuff-team! Both points have been resolved in the latest commit:

1. Blank Line Preservation & Counting: Blank lines are now counted as 1 visual line across all three paths:
   • In the collapsed preview loop: if (line.length === 0) now pushes '' to displayLines, preserving blank lines in the rendered output rather than skipping them, and breaks once maxLines visual lines are collected.
   • In off-screen line counting: blank lines increment remainingVisualLines++.
   • In isExpanded: blank lines increment totalVisual++.
   • In addition, partial wrapped-line excess is now tracked precisely (excessInProcessedLine = wrapped.length - i) when a wrapped line is truncated at the boundary.
2. Hybrid Off-Screen Line Counting: For off-screen lines, the component now uses the exact getLastNVisualLines wrapper on the first 50 off-screen lines, and applies the fast character-width estimate Math.max(1, Math.ceil(line.length / width)) for lines beyond 50. This gives exact line counts on common command outputs while preserving the performance advantage on massive (e.g. 10,000-line) logs. We've also documented this approximation in the PR summary.
3. OpenTUI Test Suite: Added test cases in cli/src/components/__tests__/terminal-command-display.test.tsx verifying:
   • Interstitial blank lines in preview are preserved and counted toward maxVisibleLines.
   • Off-screen blank lines are accurately counted in hiddenLinesCount.
   • Multi-line wrapped line boundary truncation is counted accurately.