feat(dictionary): add Hachidori backend support

- Add backend selection, setup gating, Anki integration, and external host support
- Add launcher flags, documentation, packaging, and focused tests
- Open on-demand overlay modals on the first attempt

src/main/runtime/tray-main-actions.test.ts

@@ -71,6 +71,8 @@ test('build tray template handler wires actions and init guards', () => {
     showFirstRunSetup: () => true,
     openFirstRunSetupWindow: (force?: boolean) => calls.push(force ? 'setup-forced' : 'setup'),
     showWindowsMpvLauncherSetup: () => true,
+    getDictionaryBackend: () => 'yomitan',
+    openHachidoriSettings: () => {},
     openYomitanSettings: () => calls.push('yomitan'),
     openConfigSettingsWindow: () => calls.push('configuration'),
     openSyncUiWindow: () => calls.push('sync-ui'),
@@ -127,6 +129,8 @@ test('windows mpv launcher tray action force-opens completed setup', () => {
     showFirstRunSetup: () => false,
     openFirstRunSetupWindow: (force?: boolean) => calls.push(force ? 'setup-forced' : 'setup'),
     showWindowsMpvLauncherSetup: () => true,
+    getDictionaryBackend: () => 'yomitan',
+    openHachidoriSettings: () => {},
     openYomitanSettings: () => calls.push('yomitan'),
     openConfigSettingsWindow: () => calls.push('configuration'),
     openSyncUiWindow: () => calls.push('configuration'),