fix(bookcontent): prevent single-word bar labels from wrapping an orphan letter

[kdroidFilter]

Summary

• Single-word lateral-bar button labels (e.g. מפרשים) no longer wrap an orphan final letter onto a second line at fractional display scaling (e.g. 175%). They now render on a single line with auto-shrink (10sp → 7sp only when needed) via BasicText + TextAutoSize.
• Multi-word labels (e.g. תוכן עניינים) keep their natural two-line wrap at the space.

Test plan

• Open a book; verify the מפרשים button label stays on one line at 100% and 175% display scaling.
• Verify תוכן עניינים still wraps onto two lines.
• Confirm short labels are unchanged at 10sp.