fix: remove Tab keydown interceptor, use tabIndex=-1 on buttons instead

The keydown interceptor was likely conflicting with xterm.js native
Tab handling. Instead, set tabIndex=-1 on toolbar buttons so Tab
can't escape the terminal to browser focus, and auto-refocus terminal
on any click outside the toolbar.

static/toolbar.js

@@ -111,18 +111,14 @@
     if(btn.dataset.k) send(btn.dataset.k);
   });
 
-  // Prevent browser from stealing Tab key — send it to the terminal instead
-  document.addEventListener('keydown', function(e){
-    if(e.key === 'Tab' && !e.altKey && !e.ctrlKey && !e.metaKey){
-      var active = document.activeElement;
-      // Only intercept if focus is on the terminal or body (not on toolbar buttons)
-      if(!active || active === document.body || active.closest('.xterm')){
-        e.preventDefault();
-        send('\t');
-      }
-    }
+  // Ensure terminal keeps focus (prevents Tab from escaping to browser chrome)
+  document.addEventListener('click', function(e){
+    if(!e.target.closest('#mb') && window.term) window.term.focus();
   });
 
+  // Remove tabindex from toolbar buttons so Tab can't escape to them
+  bar.querySelectorAll('button').forEach(function(b){ b.tabIndex = -1; });
+
   // Shrink terminal for toolbar on mobile (2 rows)
   var obs=new MutationObserver(function(){
     var el=document.querySelector('.xterm');