feat(migrate): daemon-update prompt + migrate-to-seed UX polish + i18n

Fixes the Windows migrate-to-seed failure (the old bundled daemon lacked
z_exportmnemonic) and rounds out the flow:

- seed_wallet_creator: actionable "daemon too old" message instead of the
  raw "Method not found" RPC error.
- Startup daemon-update prompt: if the wallet bundles a newer node than the
  installed one, offer to update it (once per version, keyed on a new
  daemon_update_prompted_size setting; never silently clobbers a custom
  node). "Install bundled" now also works when attached to an external /
  leftover daemon (RPC-stops it, then swaps + restarts).
- Migrate-to-seed Intro pre-flight: detect an already-mnemonic wallet
  (offer backup instead), an old daemon, or a locked/disconnected wallet
  before offering to create anything.
- No-funds path: a zero-balance wallet can adopt the new seed wallet
  directly (behind an acknowledgement checkbox) instead of a dead sweep.
- Loading spinners on the Working/Sweeping/Adopting steps; sweep coverage
  for the new intro / no-funds surfaces.
- Translations for all 18 new strings across 8 languages (+ rebuilt CJK
  subset font).

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

src/daemon/seed_wallet_creator.cpp

@@ -117,7 +117,19 @@ SeedWalletResult SeedWalletCreator::create(bool keepDatadir,
         r.ok = !r.seedPhrase.empty() && !r.destAddress.empty();
         if (!r.ok) r.error = "The isolated node returned an empty seed or address.";
     } catch (const std::exception& e) {
-        r.error = std::string("Seed export failed: ") + e.what();
+        const std::string what = e.what();
+        // "Method not found" (JSON-RPC -32601) means this dragonxd predates mnemonic support —
+        // it has no z_exportmnemonic RPC (the older bundled binary). Migrate-to-seed can't work
+        // until the daemon is updated, so give an actionable message, not the raw RPC error.
+        if (what.find("Method not found") != std::string::npos ||
+            what.find("-32601") != std::string::npos) {
+            r.error = "This DragonX daemon is too old to create a seed wallet — it lacks mnemonic "
+                      "support (the z_exportmnemonic RPC). Update to the latest DragonX daemon "
+                      "(Settings -> NODE & SECURITY -> Check for updates, or Install bundled), then "
+                      "try again.";
+        } else {
+            r.error = std::string("Seed export failed: ") + what;
+        }
     }
 
     // 7. Stop the isolated node (graceful; it flushes its tiny empty chain quickly).