🤖 refactor: remove VerticalTokenMeter component (#1227)

Remove VerticalTokenMeter now that we have the context usage indicator
in the chat area.

**Changes:**
- Removed `VerticalTokenMeter.tsx` and `ChatMetaSidebar.tsx` components
- Removed auto-collapse hysteresis logic (was based on chatAreaWidth)
- Added manual collapse/expand toggle using shared
`SidebarCollapseButton` component
- Both sidebars now use same collapse button style (20px width, `«»`
chevrons)
- Tab keyboard shortcuts (`Ctrl+1/2/3`) auto-expand the right sidebar if
collapsed
- Stories default to collapsed right sidebar; rightsidebar stories
explicitly expand

**Shared component:**
`src/browser/components/ui/SidebarCollapseButton.tsx`
- Used by both ProjectSidebar and RightSidebar
- `side` prop controls chevron direction
- Optional `shortcut` prop for tooltip

---
_Generated with `mux` • Model: `anthropic:claude-sonnet-4-20250514` •
Thinking: `none`_

Author: ammar-agent

src/browser/components/AIView.tsx

@@ -797,7 +797,6 @@ const AIViewInner: React.FC<AIViewProps> = ({
         key={workspaceId}
         workspaceId={workspaceId}
         workspacePath={namedWorkspacePath}
-        chatAreaRef={chatAreaRef}
         width={sidebarWidth}
         onStartResize={startResize}
         isResizing={isResizing}

src/browser/components/ChatMetaSidebar.tsx

@@ -51,7 +51,7 @@ export function LeftSidebar(props: LeftSidebarProps) {
         className={cn(
           "h-screen bg-sidebar border-r border-border flex flex-col shrink-0",
           "transition-all duration-200 overflow-hidden relative z-20",
-          collapsed ? "w-8" : "w-72",
+          collapsed ? "w-5" : "w-72",
           "mobile-sidebar",
           collapsed && "mobile-sidebar-collapsed"
         )}

src/browser/components/LeftSidebar.tsx

@@ -19,6 +19,7 @@ import {
   AGE_THRESHOLDS_DAYS,
 } from "@/browser/utils/ui/workspaceFiltering";
 import { Tooltip, TooltipTrigger, TooltipContent } from "./ui/tooltip";
+import { SidebarCollapseButton } from "./ui/SidebarCollapseButton";
 import SecretsModal from "./SecretsModal";
 import type { Secret } from "@/common/types/secrets";
 import { ForceDeleteModal } from "./ForceDeleteModal";
@@ -714,21 +715,12 @@ const ProjectSidebarInner: React.FC<ProjectSidebarProps> = ({
               </div>
             </>
           )}
-          <Tooltip>
-            <TooltipTrigger asChild>
-              <button
-                onClick={onToggleCollapsed}
-                aria-label={collapsed ? "Expand sidebar" : "Collapse sidebar"}
-                className="text-muted border-dark hover:bg-hover hover:text-foreground mt-auto flex h-9 w-full cursor-pointer items-center justify-center border-t border-none bg-transparent p-0 text-sm transition-all duration-200"
-              >
-                {collapsed ? "»" : "«"}
-              </button>
-            </TooltipTrigger>
-            <TooltipContent align="center">
-              {collapsed ? "Expand sidebar" : "Collapse sidebar"} (
-              {formatKeybind(KEYBINDS.TOGGLE_SIDEBAR)})
-            </TooltipContent>
-          </Tooltip>
+          <SidebarCollapseButton
+            collapsed={collapsed}
+            onToggle={onToggleCollapsed}
+            side="left"
+            shortcut={formatKeybind(KEYBINDS.TOGGLE_SIDEBAR)}
+          />
           {secretsModalState && (
             <SecretsModal
               isOpen={secretsModalState.isOpen}