refactor: consolidate duplicate account checking logic into unified utility

- Extract checkForDuplicateAccount methods from ImportAccountView and ImportDerivedAccountView
- Create unified utility function in src/libs/util.ts with TypeScript overloads
- Support both direct DID checking and mnemonic+derivation path checking
- Improve error handling with centralized logging via PlatformServiceFactory
- Add comprehensive JSDoc documentation for both function overloads
- Remove unused imports (deriveAddress, newIdentifier) from ImportAccountView

The utility function now provides a clean API:
- checkForDuplicateAccount(did) - for direct DID checking
- checkForDuplicateAccount(mnemonic, derivationPath) - for derivation + checking

Both components maintain identical functionality while using centralized logic.

src/views/ImportDerivedAccountView.vue

@@ -83,6 +83,7 @@ import {
   retrieveAllAccountsMetadata,
   retrieveFullyDecryptedAccount,
   saveNewIdentity,
+  checkForDuplicateAccount,
 } from "../libs/util";
 import { logger } from "../utils/logger";
 import { Account, AccountEncrypted } from "../db/tables/accounts";
@@ -172,7 +173,7 @@ export default class ImportAccountView extends Vue {
 
     try {
       // Check for duplicate account before creating
-      const isDuplicate = await this.checkForDuplicateAccount(newId.did);
+      const isDuplicate = await checkForDuplicateAccount(newId.did);
       if (isDuplicate) {
         this.notify.warning(
           "This derived account already exists. Please try a different derivation path.",
@@ -202,27 +203,5 @@ export default class ImportAccountView extends Vue {
       this.notify.error(NOTIFY_ACCOUNT_DERIVATION_ERROR.message, TIMEOUTS.LONG);
     }
   }
-
-  /**
-   * Checks if the account to be created already exists
-   *
-   * @param did - The DID to check for duplicates
-   * @returns Promise<boolean> - True if account already exists, false otherwise
-   */
-  private async checkForDuplicateAccount(did: string): Promise<boolean> {
-    try {
-      // Check if an account with this DID already exists
-      const existingAccount = await this.$query(
-        "SELECT did FROM accounts WHERE did = ?",
-        [did],
-      );
-
-      return existingAccount?.values?.length > 0;
-    } catch (error) {
-      // If we can't check for duplicates, let the save process handle the error
-      this.$logError("Error checking for duplicate account: " + error);
-      return false;
-    }
-  }
 }
 </script>