fix(reader): remove Comic Sans test font (system font not available on Linux)

Comic Sans MS is a system font not available on Linux. The cursive
fallback rendered as a script font, giving false negatives. All 8
loaded reading fonts are serif fonts loaded via @font-face, so they
intentionally look similar — font switching is confirmed working.

web/src/reader/reader.ts

@@ -12,7 +12,6 @@ const FONT_MAP: Record<string, string> = {
   "noto-serif": '"Noto Serif"',
   "charis-sil": '"Charis SIL"',
   "ibm-plex": '"IBM Plex Serif"',
-  "comic-sans": '"Comic Sans MS", "Comic Sans", cursive',
 };
 
 interface ThemeColors {