[FEATURE] Add keyboard shortcuts for common actions

[rohitkumarnaidu]

Feature Description

FlowCraft requires all interactions through mouse clicks. Power users need keyboard shortcuts.

Proposed Shortcuts

• Delete/Backspace: Delete selected block
• Ctrl+A: Select all blocks
• Ctrl+D: Duplicate selected block
• Ctrl+S: Save/export flowchart
• Escape: Deselect current block
• Tab: Cycle through blocks
• Arrow Keys: Navigate between connected blocks

Why This Matters

• Keyboard shortcuts improve productivity by 30-40%
• Essential for accessibility compliance (WCAG 2.1)
• Standard in professional diagram editors (draw.io, Lucidchart)

[rohitkumarnaidu]

Hey maintainer, I'd love to work on this issue and submit a PR. Could you please assign it to me?

[Myparadox-creator]

Hey! @Itzzavdheshh i'd like to be assigned and work under this issue [ELUSOC'26]