refactor(settings): collapse all sections, drop font dropdown, surface OpenDyslexic (#508)

* refactor(settings): collapse all sections, drop font dropdown, surface OpenDyslexic

Settings opened on a tab where four or five sub-sections were expanded
on first render — audio device, theme list, lyrics sources, sidebar
customizer, random-mix copy, offline dir, language picker, keybindings
table. The page felt like a wall of controls before the user had even
looked for something specific. Removed every `defaultOpen` flag from
the SettingsSubSection call sites so each tab now boots with only the
section headers visible. Component default was already `false`.

ThemePicker auto-expanded the group containing the active theme on
mount. Same noise on a screen that already has the longest accordion
list in the app, and the blue dot in the group header already tells
the user which group holds the active theme. Initial open-group is
now `null` — all groups collapsed until the user clicks one.

Font picker had a dropdown-style button that toggled a list inside
the sub-section, which meant two clicks (open the section, then open
the dropdown) for what should be a one-click choice. Removed the
button + the `fontPickerOpen` state — opening the Font sub-section
now reveals the full list directly and a click sets the font without
collapsing anything. OpenDyslexic moved to the top of the list so
users with dyslexia don't scroll past 14 sans-serifs to find their
option; the rest stays in the original order.

* docs: changelog entry for PR #508

Logs the Settings collapse-by-default + font picker cleanup +
OpenDyslexic ordering in v1.46.0 "## Changed".

src/components/ThemePicker.tsx

@@ -180,8 +180,10 @@ interface Props {
 }
 
 export default function ThemePicker({ value, onChange }: Props) {
-  const initialOpen = THEME_GROUPS.find(g => g.themes.some(t => t.id === value))?.group ?? THEME_GROUPS[0].group;
-  const [openGroup, setOpenGroup] = useState<string | null>(initialOpen);
+  // All groups collapsed on first render. The blue dot in the header surfaces
+  // which group holds the active theme, so auto-expanding it on mount just
+  // adds visual noise to a screen that already has a long sub-section list.
+  const [openGroup, setOpenGroup] = useState<string | null>(null);
 
   const toggle = (group: string) => setOpenGroup(prev => prev === group ? null : group);