fix: filebrowser scroll+lang hover+black-flash+shell one-line

- filebrowser: select() only scrollIntoView on keyboard, not hover
- lang-switch: .lang-switch:hover → invert rule (header excluded before)
- black-flash: color-scheme light; dark script sets colorScheme
- shell: flex-wrap nowrap; keepEnd() scrolls on input

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

assets/js/shell.js

@@ -8,8 +8,13 @@
   var input = document.querySelector(".prompt__input");
   var out = document.querySelector(".prompt__out");
   var menu = document.querySelector(".menu");
+  var promptEl = document.querySelector(".prompt");
   if (!bar || !input) return;
 
+  // keep the caret/right end in view: when the line overflows, scroll it fully
+  // right so the left (older) part clips off terminal-style instead of wrapping.
+  function keepEnd() { if (promptEl) promptEl.scrollLeft = promptEl.scrollWidth; }
+
   var home = bar.getAttribute("data-home") || "/";
 
   // command → url: the always-open menu, plus any context routes (e.g. the
@@ -307,7 +312,7 @@
       caretToEnd(); say("");
     }
   });
-  input.addEventListener("input", function () { say(""); });
+  input.addEventListener("input", function () { say(""); keepEnd(); });
 
   function caretToEnd() {
     var r = document.createRange();
@@ -316,6 +321,7 @@
     var s = window.getSelection();
     s.removeAllRanges();
     s.addRange(r);
+    keepEnd();
   }
 
   // start typing anywhere → the keystroke goes straight into the command line