good first issue: Add realistic example dataset in legacy Excel format (.xls)

[ReginaldErzoah]

Description

Add a realistic dataset in legacy Excel (.xls) format to the examples/ folder. This will help users test Aniwa's compatibility with older Excel files.

File Location

examples/example.xls

Requirements

• Format: Excel (.xls) - legacy Excel 97-2003 format
• Rows: Minimum 100 rows
• Columns: 8-15 columns
• Data: Realistic or real-world data (not random/gibberish)

How to Create

You can create an .xls file using:

• Microsoft Excel (Save As --> Excel 97-2003 Workbook)
• Google Sheets (export as .xls)
• LibreOffice Calc

Data Characteristics

Include realistic data patterns:

• Some null/missing values
• Mixed data types (strings, numbers, dates)
• First row should contain column headers

Note: .xls has limitations (65,536 max rows, 256 max columns) - stay well within these limits.

Testing

aniwa profile examples/example.xls

Acceptance Criteria

• File created at examples/example.xls
• Minimum 100 rows of data (plus header row)
• Valid legacy .xls format
• Loads without errors in Aniwa