Replace the boolean large-text flag with three global typography tiers,
defaulting new installs to the smallest tier when English is in effect
while preserving legacy storage and Chinese defaults. Add a profile
sub-screen to pick the tier and unit tests for storage resolution.
Co-authored-by: Cursor <cursoragent@cursor.com>
Share font size, font family, and background across all memoir chapters via MemoirReadingSettingsProvider and SecureStore (same app-settings pattern). Add parse/merge helpers and unit tests.
Co-authored-by: Cursor <cursoragent@cursor.com>
