Variable sidebar should be collapsed by default when opening notebooks

[celeria-ai]

Problem Description

When opening a notebook, the Variables sidebar on the right is expanded by default. This takes up screen real estate and is not needed for most notebook operations—users typically only need to see variable values after running cells. The sidebar should be collapsed by default to maximize the notebook content area and provide a cleaner initial view.

Root Cause

In src/renderer/components/NotebookViewer.tsx, the variable panel state is initialized to true:

// Line 128
const [showVariablesPanel, setShowVariablesPanel] = useState(true);

This causes the sidebar to render expanded immediately when the notebook component mounts.

Proposed Fix

Change the initial state to false so the variable sidebar is collapsed by default:

File: src/renderer/components/NotebookViewer.tsx
Location: Line 128

const [showVariablesPanel, setShowVariablesPanel] = useState(false);

Expected Behavior

When opening a notebook, the variable sidebar should appear collapsed (minimized) on the right side. Users can still expand it by clicking the panel toggle button if they want to view or explore variables.

This change improves the initial user experience by prioritizing the notebook content area and reducing visual clutter for users who are just reading or editing notebooks without needing immediate variable inspection.