feat: add Ctrl+Alt key remapping for browser-blocked shortcuts (#501)

Browsers intercept Ctrl+W/T/N/Q, making them unusable in terminal.
This adds Ctrl+Alt+<key> as an alternative that sends Ctrl+<key>.

- Ctrl+Alt+W → Ctrl+W (nano search, delete word)
- Ctrl+Alt+T → Ctrl+T (transpose chars)
- Ctrl+Alt+N → Ctrl+N (next line)
- Ctrl+Alt+Q → Ctrl+Q (XON flow control)

Fixes Termix-SSH/Support#407

src/ui/desktop/apps/features/terminal/Terminal.tsx

@@ -1349,6 +1349,24 @@ export const Terminal = forwardRef<TerminalHandle, SSHTerminalProps>(
           return true;
         }
 
+        // Ctrl+Alt+<key> → Ctrl+<key> remapping for browser-blocked shortcuts
+        // Browsers intercept Ctrl+W/T/N/Q, so we use Ctrl+Alt as an alternative
+        if (e.ctrlKey && e.altKey && !e.metaKey && !e.shiftKey) {
+          const key = e.key.toLowerCase();
+          const blockedKeys = ["w", "t", "n", "q"];
+          if (blockedKeys.includes(key)) {
+            e.preventDefault();
+            e.stopPropagation();
+            const ctrlCode = key.charCodeAt(0) - 96;
+            if (webSocketRef.current?.readyState === 1) {
+              webSocketRef.current.send(
+                JSON.stringify({ type: "input", data: String.fromCharCode(ctrlCode) }),
+              );
+            }
+            return false;
+          }
+        }
+
         if (showAutocompleteRef.current) {
           if (e.key === "Escape") {
             e.preventDefault();