Add undo/redo functionality with toolbar buttons and keyboard shortcuts Fixes #359

[kundangosavii]

Description

Adds comprehensive undo/redo functionality to DoodleBUGS interface as requested in issue #359.

Features Added

• Undo/redo buttons in canvas toolbar
• Keyboard shortcuts: Ctrl+Z (undo) and Ctrl+Shift+Z/Ctrl+Y (redo)
• Integration with cytoscape-undo-redo for graph operations

Technical Implementation

• UndoRedoControls.vue: New component with toolbar buttons
• useUndoRedo.ts: Composable for centralized undo/redo logic
• cytoscape-undo-redo: External library integration with TypeScript definitions
• useGraphInstance.ts: Enhanced with undo-redo initialization
• GraphCanvas.vue: Fixed onMounted callback structure (was preventing graph rendering)

Testing

• Buttons enable/disable based on available actions
• Keyboard shortcuts work globally (except in input fields)
• Node dragging operations are undoable

doodlebug.v1.mp4

Files Changed

• Added: src/components/ui/UndoRedoControls.vue
• Added: src/composables/useUndoRedo.ts
• Added: src/types/cytoscape-undo-redo.d.ts
• Modified: package.json (added cytoscape-undo-redo dependency)
• Modified: Canvas toolbar, GraphInstance, GraphElements composables

Fixes #359

[kundangosavii]

@shravanngoswamii , I accidentally unassigned myself from this issue. Could you please reassign it to me? Sorry for confusion.