[Insight extractor] Feature: Collapsible Sidebar with Expand Icon

Description
When the user clicks the collapse button on the sidebar, the entire sidebar should be hidden. Currently, only part of the sidebar is hidden. Once collapsed, an expand icon should appear in the top navigation bar to allow the user to restore the sidebar.

Requirements

Collapse Behavior

Clicking the collapse button hides the sidebar completely (not partially).

The main content area should automatically expand to use the freed space.

Expand Behavior

When the sidebar is collapsed, an expand icon appears in the top navigation bar.

Clicking this expand icon restores the sidebar to its full width.

UI/UX

Collapse button: positioned inside the sidebar (top-left-corner).

Expand button: positioned inside the top navigation bar (left side).

Use consistent icons (e.g., left/right chevrons) to indicate collapse/expand actions.

Smooth transition animation (e.g., slide in/out or width transition) preferred.

Acceptance Criteria

✅ Sidebar fully disappears when collapse button is clicked.

✅ Top navigation bar shows expand icon when sidebar is collapsed.

✅ Clicking expand icon restores sidebar to full width.

✅ No layout overlap — main content expands/shrinks correctly.

✅ Behavior works across all screen sizes.