fix : replaced alert with inline error in Analytics.jsx image export

[tmdeveloper007]

Summary of What Has Been Done

Replaced the browser alert() call in the Analytics page image export handler with a state-based inline error message for better UX.

Changes Made

• Added exportError state to the Analytics component
• Cleared exportError at the start of exportToImage
• Replaced alert() with setExportError() on catch
• Added inline error display below the export buttons

Impact it Made

• Eliminates jarring browser dialog on export failure
• Works properly on mobile
• Consistent with the app's UX patterns

Note: Please assign this PR to the tmdeveloper007 account.