Improve error reporting for users

[LukasWallrich]

Summary

Currently, when errors occur in the FReD Explorer or FLoRA Annotator apps, users don't have a clear way to understand what went wrong or how to report the issue.

Suggested improvements

1. User-friendly error messages: Replace technical error messages with clear, actionable descriptions
2. Error toast/notification system: Show non-blocking error notifications that don't disrupt the user flow
3. Include context in error reports: When an error occurs, provide an easy way to include relevant context (e.g., what action was being performed, browser info, data state)
4. Pre-fill error reports: Consider adding a "Report this error" button that opens the feedback email with error details pre-filled
5. Console logging for debugging: Ensure all errors are logged to console with full stack traces for developers

Areas to review

• Data loading errors (CSV parsing, network failures)
• DOI lookup failures
• PDF parsing errors
• Chart rendering errors
• DataTables initialization/update errors

Related

A feedback link has been added to the footer of both apps to make it easier for users to report issues.

[LukasWallrich]

Duplicates #3 in terms of what we would do