feat(lite): Console tab with connection + open/create diagnostics

The lite variant had no visibility into why a wallet failed to open — just a
"disconnected" spinner. Add a lite-only Console tab (full-node keeps its RPC
console) that shows a live diagnostic log.

- LiteDiagnostics: a small thread-safe, bounded ring buffer (header-only). The
  controller writes to it from its background threads: each failover server
  attempt and result, wallet open/create/restore outcomes, sync start, and
  blocked-open reasons. The App logs controller (re)builds with the preferred
  server.
- lite_console_tab: a terminal-styled, read-only view of the log (newest at the
  bottom, error/success lines coloured) with Clear / Copy / Auto-scroll. Reachable
  even when the wallet is locked (it's diagnostics, no secrets). Registered as
  NavPage::LiteConsole, gated lite-only via WalletUiSurface::LiteConsole.

A unit test drives an open-with-failover and asserts the log records the
connection attempt and the successful open. Built clean for full-node, lite, and
Windows cross-compile.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/wallet/wallet_capabilities.h

@@ -43,7 +43,8 @@ enum class WalletUiSurface {
     BootstrapDownload,
     SetupWizard,
     NodeSettings,
-    LiteNetwork   // lite-wallet-only server browser (replaces Peers in lite builds)
+    LiteNetwork,  // lite-wallet-only server browser (replaces Peers in lite builds)
+    LiteConsole   // lite-wallet-only diagnostics console (full-node uses the RPC Console)
 };
 
 struct WalletCapabilities {
@@ -155,6 +156,7 @@ constexpr bool isUiSurfaceAvailable(const WalletCapabilities& capabilities,
         case WalletUiSurface::Explorer:
             return capabilities.fullNodePagesAvailable;
         case WalletUiSurface::LiteNetwork:
+        case WalletUiSurface::LiteConsole:
             return !capabilities.fullNodePagesAvailable;  // lite builds only
         case WalletUiSurface::BootstrapDownload:
         case WalletUiSurface::SetupWizard: