Add font import for Now, Gotham and Open Sauce One overrides; package fonts for Void

Font import:
- Migration M6 adds user_fonts; files are stored content-addressed under
  the local data dir. New Rust commands inspect, import, list, read and
  remove fonts, refusing WOFF2, collections, variable fonts and
  restricted fsType, and unpacking WOFF1 to plain sfnt.
- Imported fonts register in the render worker as user:<Face> families
  with an italic alias, and are pinned in the frozen render prefs so
  issued invoices can still re-render. Fonts referenced by issued
  invoices are hidden, never deleted.
- Size and tracking compensations tuned for the substitutes apply only
  while the face is not overridden; default output and fingerprint
  goldens are unchanged.
- Settings gets a Fonts section with a licence acknowledgement.

Void packaging:
- Install fonts to /usr/share/fonts/voiced with per-family OFL licences,
  set font_dirs, and add INSTALL/REMOVE scripts that run fc-cache.
  xbps-create carries both scripts (verified in a void-glibc container).
- Fix xbps-create dependency specs in build-xbps.sh.

src/hooks/useUserFonts.ts

@@ -0,0 +1,23 @@
+import { useEffect, useState } from "react";
+import { api } from "../lib/api";
+import { onUserFontsChanged, type UserFontRow } from "../lib/fontImport";
+
+/** The visible user-imported fonts; reloads when the Settings font table changes them. Empty while loading or on error. */
+export function useUserFonts(): UserFontRow[] {
+  const [fonts, setFonts] = useState<UserFontRow[]>([]);
+  useEffect(() => {
+    let active = true;
+    const load = () =>
+      api
+        .listUserFonts()
+        .then((rows) => active && setFonts(rows))
+        .catch(() => active && setFonts([]));
+    void load();
+    const off = onUserFontsChanged(() => void load());
+    return () => {
+      active = false;
+      off();
+    };
+  }, []);
+  return fonts;
+}