refactor(branding): rename app Tanemaki → Tane

Public name is now Tane (種, "seed"); Tanemaki (種まき, "to scatter seeds")
is kept only as etymology in the About screen and onboarding.

App not yet distributed, so format tokens rename cleanly with no migration:
backup extension .tanemaki→.tane, QR scheme tanemaki://→tane://, file
prefixes tane-*. Website link and species-catalog User-Agent →
tane.comunes.org. Android label capitalised to "Tane".

Identity/crypto constants already use org.comunes.tane (derivation, HKDF
backup, sync namespace, TANE1 recovery tag) — left untouched, so keys,
backups and sync are unaffected. Tests updated; analyze + full suite green.

apps/app_seeds/test/ui/small_screen_overflow_test.dart

@@ -43,7 +43,7 @@ void main() {
   const longLocales = [AppLocale.es, AppLocale.pt, AppLocale.ast];
 
   setUpAll(() => PackageInfo.setMockInitialValues(
-        appName: 'Tanemaki',
+        appName: 'Tane',
         packageName: 'org.comunes.tane',
         version: '0.1.0',
         buildNumber: '1',