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.

README.md

@@ -108,12 +108,20 @@ Launch **Voiced** from the application menu, or run `voiced`. Remove it with
 The package installs `/usr/bin/voiced`, a desktop entry and hicolor icons, and depends on
 `libwebkit2gtk41`.
 
+**Fonts on Void.** The package also installs the bundled TTF fonts under
+`/usr/share/fonts/voiced/<family>/` and each family's OFL licence under
+`/usr/share/licenses/voiced/`. The `voiced/` subdirectory avoids file conflicts with Void's own
+`font-ibm-plex-ttf` and `noto-fonts-ttf`. The `INSTALL` and `REMOVE` scripts in `packaging/void/`
+run `fc-cache -f /usr/share/fonts/voiced` after install and removal. `xbps-create` packs them from
+the destdir root (checked with xbps 0.60.7).
+
 ### Building through xbps-src
 
 Copy `packaging/void/template` into a `void-packages` checkout and build it the standard way:
 
 ```bash
-cp -r packaging/void/template void-packages/srcpkgs/voiced/template
+mkdir -p void-packages/srcpkgs/voiced
+cp packaging/void/template packaging/void/INSTALL packaging/void/REMOVE void-packages/srcpkgs/voiced/
 cd void-packages && ./xbps-src pkg voiced
 ```