fix(web): address review feedback on the monitoring column (#1616)

- ResizeHandle: clear the `resizing-col` body class on unmount so a drag
  interrupted by the handle unmounting (narrow past the breakpoint / disconnect)
  can't leave page-wide user-select:none / col-resize applied.
- Embedded monitor column now shows the full unfiltered stream instead of
  silently mirroring the full-size screen's live filter (the column has no
  filter control to explain an empty/partial list).
- MonitoringControls: give the SegmentedControl an aria-label ("Monitoring
  screen") so the tab group has an accessible name.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/web/src/components/elements/ResizeHandle/ResizeHandle.test.tsx

@@ -86,6 +86,28 @@ describe("ResizeHandle", () => {
     expect(document.body.classList.contains("resizing-col")).toBe(false);
   });
 
+  it("clears the drag body class if it unmounts mid-drag", () => {
+    const onChange = vi.fn();
+    const onCommit = vi.fn();
+    const { unmount } = renderWithMantine(
+      <ResizeHandle
+        value={400}
+        min={320}
+        max={720}
+        onChange={onChange}
+        onCommit={onCommit}
+      />,
+    );
+    fireEvent.pointerDown(screen.getByRole("separator"), {
+      clientX: 500,
+      pointerId: 1,
+    });
+    expect(document.body.classList.contains("resizing-col")).toBe(true);
+    // No pointerup/cancel — the handle is removed from the tree first.
+    unmount();
+    expect(document.body.classList.contains("resizing-col")).toBe(false);
+  });
+
   it("ignores pointer moves when no drag is active", () => {
     const { handle, onChange, onCommit } = setup();
     fireEvent.pointerMove(handle, { clientX: 460, pointerId: 1 });

clients/web/src/components/elements/ResizeHandle/ResizeHandle.tsx

@@ -1,4 +1,9 @@
-import { useRef, type KeyboardEvent, type PointerEvent } from "react";
+import {
+  useEffect,
+  useRef,
+  type KeyboardEvent,
+  type PointerEvent,
+} from "react";
 import { Box } from "@mantine/core";
 
 export interface ResizeHandleProps {
@@ -45,6 +50,13 @@ export function ResizeHandle({
   // Gesture origin, captured on pointer down. `null` while idle.
   const drag = useRef<{ startX: number; startWidth: number } | null>(null);
 
+  // If the handle unmounts mid-drag — the window narrows past the split
+  // breakpoint or the server disconnects, either of which removes the handle
+  // from the tree before a pointerup/cancel fires — the drag body class would
+  // otherwise linger and leave `user-select: none` + `col-resize` applied
+  // page-wide. Clear it on unmount so the class is self-healing.
+  useEffect(() => () => document.body.classList.remove("resizing-col"), []);
+
   function handlePointerDown(e: PointerEvent<HTMLDivElement>) {
     drag.current = { startX: e.clientX, startWidth: value };
     // Optional chaining: happy-dom (unit tests) doesn't implement pointer