feat(desktop): move dictionary entries in and out as files

Users could only rebuild their spoken-word dictionary entry by entry. Import
and export now round-trip the whole list, reporting duplicate and invalid
entries per row instead of failing the batch, so a dictionary survives a
reinstall or a move to another machine.

apps/desktop/src/main/ipc/dictionary-handlers.ts

@@ -1,6 +1,6 @@
 // src/main/ipc/dictionary-handlers.ts
 
-import { ipcMain } from 'electron'
+import { ipcMain, dialog } from 'electron'
 import { IPC_CHANNELS } from '@d3ro/core/ipc-channels'
 import { ipcSuccess, ipcError, ErrorCode, D3ROError } from '@d3ro/core/errors'
 import { getDictionaryService } from '../services/DictionaryService'
@@ -9,7 +9,9 @@ import type {
   DictionaryAddParams,
   DictionaryUpdateParams,
   DictionaryDeleteParams,
-  DictionarySearchParams
+  DictionarySearchParams,
+  DictionaryImportParams,
+  DictionaryExportParams
 } from '@d3ro/core/types'
 
 export function registerDictionaryHandlers(): void {
@@ -74,4 +76,43 @@ export function registerDictionaryHandlers(): void {
       return ipcError(ErrorCode.DBQueryFailed, `Failed to search dictionary: ${message}`)
     }
   })
+
+  ipcMain.handle(IPC_CHANNELS.DICTIONARY.IMPORT, async (_event, params: DictionaryImportParams) => {
+    try {
+      let filePath = params.filePath
+      if (!filePath) {
+        const picked = await dialog.showOpenDialog({
+          properties: ['openFile'],
+          filters: [
+            params.format === 'csv'
+              ? { name: 'CSV', extensions: ['csv'] }
+              : { name: 'JSON', extensions: ['json'] }
+          ]
+        })
+        if (picked.canceled || picked.filePaths.length === 0) {
+          return ipcSuccess({ imported: 0, skipped: 0, errors: 0 })
+        }
+        filePath = picked.filePaths[0]
+      }
+      return ipcSuccess(getDictionaryService().importDictionary({ ...params, filePath }))
+    } catch (error) {
+      if (error instanceof D3ROError) {
+        return ipcError(error.code, error.message)
+      }
+      const message = error instanceof Error ? error.message : String(error)
+      return ipcError(ErrorCode.DictionaryImportFailed, `Failed to import dictionary: ${message}`)
+    }
+  })
+
+  ipcMain.handle(IPC_CHANNELS.DICTIONARY.EXPORT, async (_event, params: DictionaryExportParams) => {
+    try {
+      return ipcSuccess(await getDictionaryService().exportDictionary(params))
+    } catch (error) {
+      if (error instanceof D3ROError) {
+        return ipcError(error.code, error.message)
+      }
+      const message = error instanceof Error ? error.message : String(error)
+      return ipcError(ErrorCode.DictionaryExportFailed, `Failed to export dictionary: ${message}`)
+    }
+  })
 }