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/views/AppSettings.tsx

@@ -36,6 +36,7 @@ import { emailError, ifscError, panError, phoneError, vendorGstinError } from ".
 import { ImagePicker } from "../components/ImagePicker";
 import { LogoBranding } from "../components/LogoBranding";
 import DiagnosticsPanel from "../components/DiagnosticsPanel";
+import { FontOverrideTable } from "../components/FontOverrideTable";
 
 const blankBank = (): BankAccount => ({
   id: null,
@@ -289,6 +290,13 @@ export default function AppSettings({
         </Tile>
       </section>
 
+      <section className="voiced-stack" style={{ marginBottom: "2.5rem" }}>
+        <h3>Fonts</h3>
+        <Tile>
+          <FontOverrideTable />
+        </Tile>
+      </section>
+
       <section className="voiced-stack" style={{ marginBottom: "2.5rem" }}>
         <h3>Defaults</h3>
         <Grid narrow>