Make typography choosable instead of hardcoded

Theme.qml was the largest remaining thing in this desktop that could
only be changed by editing a file, and typeface is the first thing
someone changes when they want a desktop to feel like theirs. Interface
font, icon font, and the base text size are settings now.

The two font choices are deliberately separate lists. Theme.fontMono is
used only to draw glyphs -- workspace pills, the status cluster, search
icons -- so a plain monospace family there replaces every icon in the
shell with tofu. The picker offers only Nerd Fonts for that slot and
says why.

Candidates are rendered in the family they name. A list of font names
set in the current font tells you nothing about what you are choosing.

The four type sizes derive from the base rather than being stored
separately, so the relationship between body, caption, heading and title
survives a change instead of four numbers drifting apart.

hypr/looks.lua reads the same key. Following the preference only on the
QML side would leave the compositor and the shell disagreeing about the
interface font, which nobody notices until a tooltip renders in a
different typeface.

Only a family this machine reports is accepted: the value reaches
hl.config as a string, and a settings file moved between machines will
name fonts that are not installed. A missing family is reported rather
than silently substituted by fontconfig.

Also collapses the wallpaper grid to two rows. Sixty tiles is two
screens of pictures on a page that also holds typography, window
geometry and effects -- everything below it was unreachable without
scrolling past all of them.

Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L

config/dot/hypr/looks.lua

@@ -115,7 +115,11 @@ hl.config({
         disable_hyprland_logo    = true,
         disable_splash_rendering = true,
 
-        font_family = "Adwaita Sans",
+        -- Same setting as Theme.fontFamily in the shell. If only the QML side
+        -- followed the preference, the compositor and the shell would disagree
+        -- about the interface font and nobody would notice until a tooltip
+        -- rendered in a different typeface.
+        font_family = prefs.get("interfaceFont", "Adwaita Sans"),
 
         -- Variable refresh rate. 3 = enable only for fullscreen windows whose
         -- content type is "video" or "game" -- the tag rules.lua applies to