polish(lite): lite-appropriate wording for no-wallet/connection states

In lite builds there is no daemon, and isConnected() now tracks the lite wallet,
so the full-node "not connected / waiting for daemon" wording was misleading when
no wallet is open. Add two strings (lite_no_wallet, lite_no_wallet_short; English
built-ins, so other languages fall back until translated) and use them in lite:

- receive/send address preview + receive empty-state overlay + send "can't send"
  tooltip + transactions empty state -> "No wallet open [— create or open one in
  Settings]" instead of daemon wording.
- Status bar: the red indicator shows "No wallet open" (not "Disconnected") in
  lite; the P2P peer count is skipped (lite has no peers); and the redundant
  full-node connection-detail line is suppressed (connection_status_ set to
  "Connected"/"" from the lite wallet state).

Full-node wording unchanged (all gated on isLiteBuild()). Build + run clean
(no RPC noise), tests pass.

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

src/util/i18n.cpp

@@ -575,7 +575,11 @@ void I18n::loadBuiltinEnglish()
         strings_["export_viewing_key"] = "Export Viewing Key";
         strings_["show_qr_code"] = "Show QR Code";
         strings_["not_connected"] = "Not connected to daemon...";
-        
+        // Lite build: there is no daemon — these replace the daemon-centric "not connected"
+        // strings when no wallet is open (isConnected() tracks the lite wallet in lite builds).
+        strings_["lite_no_wallet"] = "No wallet open — create or open one in Settings";
+        strings_["lite_no_wallet_short"] = "No wallet open";
+
         // Send Tab
         strings_["pay_from"] = "Pay From";
         strings_["send_to"] = "Send To";