feat(wallet): new/import wallets + multi-wallet i18n (P3)

Completes the wallet-files dialog and localizes the feature.

- Create a new wallet: a name is normalized to wallet-<name>.dat and opened
  via switchToWallet; the daemon mints it (seed-backed, -usemnemonic=1) on
  first load. Rejects blank names + name collisions.
- Import: out-of-datadir wallets get an Import action that copies the file
  into the datadir (never overwriting) under a wallet-*.dat name, then opens
  it — the daemon only loads plain filenames from the datadir.
- i18n: the 32 new multi-wallet / per-wallet-contacts / mining-payout strings
  translated into all 8 languages (de/es/fr/ja/ko/pt/ru/zh), CJK subset font
  rebuilt. Verified: the Chinese Wallets dialog renders with no missing glyphs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/util/i18n.cpp

@@ -270,6 +270,15 @@ void I18n::loadBuiltinEnglish()
         strings_["wallets_folder_hint"] = "/path/to/folder with wallet .dat files";
         strings_["wallets_add"] = "Add folder";
         strings_["wallets_folder_invalid"] = "That folder doesn't exist.";
+        strings_["wallets_import"] = "Import";
+        strings_["wallets_new_label"] = "Create a new wallet:";
+        strings_["wallets_new_hint"] = "Name (e.g. savings)";
+        strings_["wallets_create"] = "Create wallet";
+        strings_["wallets_name_invalid"] = "Please enter a valid wallet name.";
+        strings_["wallets_exists"] = "A wallet with that name already exists.";
+        strings_["wallets_imported"] = "Wallet imported — switching…";
+        strings_["wallets_import_failed"] = "Could not import that wallet file.";
+        strings_["wallets_creating"] = "Creating wallet — the node will restart…";
         strings_["tt_seed_migrate"] = "Create a new seed-phrase wallet and move your funds into it";
         // Migrate-to-seed modal
         strings_["mig_title"] = "Migrate to a seed wallet";