feat(workspace): frameless console that blends into its card

The tab bar and terminal lose their bordered box: the bar keeps one
divider with an accent underline on the active tab, and the terminal is
painted in the card's colour (--surface-3) instead of the page's.

That made a long-standing overflow visible: xterm re-measures its cell
only on a font option change or a resize, so a webfont landing after
open left the fit on the fallback font's cell and the rows/cols spilled
out of the pane. Re-set the family and refit on document.fonts
loadingdone.

client/src/components/run/ConsoleTabs.tsx

@@ -99,20 +99,22 @@ export function ConsoleTabs({
     "flex w-full items-center gap-2.5 rounded-md px-2.5 py-1.5 text-left text-sm text-fg-secondary hover:bg-surface-4 hover:text-fg-primary";
 
   return (
-    <div className="flex h-10 shrink-0 items-stretch rounded-t-lg border border-b-0 border-border bg-surface-2">
+    <div className="flex h-10 shrink-0 items-stretch border-b border-border">
       <div role="tablist" aria-label={t("tabs.label")} className="flex min-w-0 items-stretch">
         {tabs.map((r) => {
           const active = r.id === activeRunId;
           return (
             <div
               key={r.id}
-              className={`group relative flex min-w-0 max-w-[15rem] items-center border-r border-border ${
+              className={`group relative flex min-w-0 max-w-[15rem] items-center rounded-t-md ${
                 active
-                  ? "bg-surface-0 text-fg-primary"
-                  : "text-fg-muted hover:bg-surface-3 hover:text-fg-secondary"
+                  ? "text-fg-primary"
+                  : "text-fg-muted hover:bg-surface-4 hover:text-fg-secondary"
               }`}
             >
-              {active && <span className="absolute inset-x-0 top-0 h-0.5 bg-accent" />}
+              {active && (
+                <span className="absolute inset-x-2 -bottom-px h-0.5 rounded-full bg-accent" />
+              )}
               <button
                 type="button"
                 role="tab"