Choose a font in Settings, beside the theme (#359)

Kept as the theme is, in a cookie each browser its own, and put on the
page by boot.js before the first frame. Theme's own, the default, adds
no rule, so Modern's Inter, Classic's Lucida Grande and Glass's system
face are as they were. The others are on the device already or served
by ipx (Inter), so choosing one downloads nothing. Their rules are
last in app.css, where they tie with each theme's own body font and win.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- A font of your choosing in Settings, beside the theme: Inter, your system's, serif or monospace, kept by each browser as the theme is. Theme's own, the default, keeps each theme's face as it was (#359).
+
 ## [1.3.0] - 2026-10-23
 
 ### Fixed