feat(wallet): richer detail in the wallet-switch progress modal

The switch modal now shows more than a bare phase line:
- The title carries the target wallet ("Switching wallet — savings") and a
  "from <previous>" caption for context (names prettified: wallet.dat → "Default
  wallet", wallet-<name>.dat → "<name>", in-place links → "External wallet").
- During the Reconnecting phase — the ~30-60s where the node loads the block
  index, verifies, and rescans — it surfaces the node's LIVE init stage
  (state_.warmup_status/description via the existing translateWarmup mapping:
  "Loading blockchain data…", "Verifying blockchain…", "Scanning for
  transactions…") instead of a static "Reconnecting…".
- An elapsed timer (m:ss) so the wait visibly progresses.

i18n: from/elapsed/default-wallet/external-wallet labels (EN + 8 languages,
additive; no new CJK glyphs). No switch-flow logic change.

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

src/util/i18n.cpp

@@ -1053,6 +1053,10 @@ void I18n::loadBuiltinEnglish()
         strings_["switch_progress_reconnecting"] = "Reconnecting";
         strings_["switch_progress_hint"] = "A graceful shutdown can take up to a minute.";
         strings_["switch_progress_background"] = "Continue in background";
+        strings_["switch_progress_from_label"] = "from";
+        strings_["switch_progress_elapsed"] = "Elapsed";
+        strings_["switch_progress_default_wallet"] = "Default wallet";
+        strings_["switch_progress_external_wallet"] = "External wallet";
 
         // Receive Tab
         strings_["receiving_addresses"] = "Your Receiving Addresses";