test(i18n,sub): clear the three standing vitest reds (item 10)

- i18n dead keys: drop 13 keys with no reference left (pages.xray.routeTester*
  from the P9 feature removal, tgbot.online superseded by tgbot.messages.online,
  tgbot.commands.restartSuccess/restartFailed from the rewritten restart handler)
- i18n key sets: add the P9 forwarding block (20 keys) to the 11 locales that
  missed it, as English placeholders per repo convention; all 13 locales now
  carry identical key sets
- subscription port test: the case predated P7 — clearing the port field is the
  explicit subPort 0 (no port in generated links) opt-in via onNumber onClear,
  so assert updateSetting is called with { subPort: 0 } instead of never called

No component code, UI behavior, or styles touched.

frontend/src/test/subscription-general-tab.test.tsx

@@ -17,7 +17,12 @@ function LocationProbe() {
 }
 
 describe('SubscriptionGeneralTab', () => {
-  it('keeps the stored subscription port when the field is cleared', () => {
+  // P7 made the subscription port optional: clearing the field applies
+  // subPort 0, the explicit "no port in generated links" setting (the sub
+  // server keeps binding the default port). This field opts out of the
+  // shared keep-stored-value-on-clear semantic via onNumber's onClear —
+  // see utils/onNumber.ts and SettingService.BuildSubURIBase.
+  it('applies subPort 0 (no port in generated links) when the field is cleared', () => {
     const updateSetting = vi.fn();
 
     renderWithProviders(
@@ -33,8 +38,7 @@ describe('SubscriptionGeneralTab', () => {
     fireEvent.change(portInput, { target: { value: '' } });
     fireEvent.blur(portInput);
 
-    expect(updateSetting).not.toHaveBeenCalled();
-    expect((portInput as HTMLInputElement).value).toBe('2096');
+    expect(updateSetting).toHaveBeenCalledWith({ subPort: 0 });
   });
 
   it('forwards typed subscription ports unchanged', () => {