Replace three inconsistent error display patterns with the centralized
showError()/hideError() helpers from helpers.js:
- approval.js: replace direct DOM classList toggling for approve-tx-error
and approve-sign-error with showError/hideError calls
- addressDetail.js: replace export-privkey-flash direct DOM with
showError/hideError using renamed export-privkey-error element
- deleteWallet.js: replace delete-wallet-flash direct DOM with
showError/hideError using renamed delete-wallet-error element
- addWallet.js: replace showFlash() validation errors with dedicated
add-wallet-error div and showError/hideError calls
- importKey.js: replace showFlash() validation errors with dedicated
import-key-error div and showError/hideError calls
- index.html: add error divs for add-wallet and import-key views,
rename export-privkey-flash to export-privkey-error,
rename delete-wallet-flash to delete-wallet-error,
remove inconsistent text-red-500 class
Closes#87
