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/about_screen_test.dart

@@ -17,7 +17,7 @@ void main() {
 
   setUp(() {
     PackageInfo.setMockInitialValues(
-      appName: 'Tanemaki',
+      appName: 'Tane',
       packageName: 'org.comunes.tane',
       version: '0.1.0',
       buildNumber: '1',
@@ -38,7 +38,7 @@ void main() {
     await tester.tap(find.text('About')); // drawer entry
     await tester.pumpAndSettle();
 
-    expect(find.text('種まき'), findsOneWidget);
+    expect(find.text('種'), findsOneWidget);
     expect(find.textContaining('digital Plantare'), findsOneWidget);
     await disposeTree(tester);
   });
@@ -57,12 +57,12 @@ void main() {
     await tester.pumpAndSettle();
 
     // The backup section pushed the About tile below the fold.
-    await tester.scrollUntilVisible(find.text('About Tanemaki'), 200);
-    await tester.tap(find.text('About Tanemaki'));
+    await tester.scrollUntilVisible(find.text('About Tane'), 200);
+    await tester.tap(find.text('About Tane'));
     await tester.pumpAndSettle();
 
     // Explanation text and kanji are shown above the fold.
-    expect(find.text('種まき'), findsOneWidget);
+    expect(find.text('種'), findsOneWidget);
     expect(find.textContaining('helps people and collectives'), findsOneWidget);
     expect(find.textContaining('digital Plantare'), findsOneWidget);
 
@@ -87,8 +87,8 @@ void main() {
     await tester.pumpAndSettle();
     await tester.tap(find.text('Settings'));
     await tester.pumpAndSettle();
-    await tester.scrollUntilVisible(find.text('About Tanemaki'), 200);
-    await tester.tap(find.text('About Tanemaki'));
+    await tester.scrollUntilVisible(find.text('About Tane'), 200);
+    await tester.tap(find.text('About Tane'));
     await tester.pumpAndSettle();
 
     await tester.scrollUntilVisible(find.text('Open-source licenses'), 200);

apps/app_seeds/test/ui/backup_section_test.dart

@@ -109,12 +109,12 @@ void main() {
     expect(find.text('Copy saved'), findsOneWidget);
   });
 
-  testWidgets('saving a backup writes a sealed .tanemaki file', (tester) async {
+  testWidgets('saving a backup writes a sealed .tane file', (tester) async {
     await tester.pumpWidget(section());
     await tester.tap(find.text('Save a backup'));
     await tester.pumpAndSettle();
 
-    expect(files.savedName, endsWith('.tanemaki'));
+    expect(files.savedName, endsWith('.tane'));
     expect(BackupBox.looksSealed(files.savedBytes!), isTrue);
     expect(find.text('Copy saved'), findsOneWidget);
   });
@@ -210,7 +210,7 @@ void main() {
     await tester.pumpAndSettle();
 
     expect(
-      find.text('This file could not be read as a Tanemaki copy'),
+      find.text('This file could not be read as a Tane copy'),
       findsOneWidget,
     );
   });
@@ -228,7 +228,7 @@ void main() {
     await tester.tap(find.byKey(const Key('backup.recoverySave')));
     await tester.pumpAndSettle();
 
-    expect(files.savedName, 'tanemaki-recovery.pdf');
+    expect(files.savedName, 'tane-recovery.pdf');
     expect(String.fromCharCodes(files.savedBytes!.take(5)), '%PDF-');
     // The seed itself never appears in the clear in the PDF stream metadata;
     // the QR encodes the human code, which IS the secret — that's the point

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',