docs: Add CSV File Merger recipe

[the-matrixneo]

This pull request adds a new recipe for merging multiple CSV files in a directory into a single master file. The recipe includes built-in extension support to handle both the merging logic and filesystem operations.

• Introduces a csv-file-merger.yaml recipe that guides users through combining multiple CSV files, with validation for directory existence, header consistency options (strict or flexible), and customizable output filename.
• Defines parameters such as directory_path, output_filename, and header_check for user input .
• Specifies activities including directory validation, CSV file scanning, header consistency checks, data merging, and output file generation.
• Integrates extensions for orchestrating merging logic (developer) and handling filesystem operations (filesystem).
• Provides a user-facing prompt outlining the merging workflow and error handling for missing directories, no CSV files, or header mismatches.

Type of Change

• Feature
• Bug fix
• Refactor / Code quality
• Performance improvement
• Documentation
• Tests
• Security fix
• Build / Release
• Other (specify below)

Related Issues

Relates to #4766

Email: dakshatamishralakshya@gmail.com

[github-actions]

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[github-actions]

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[taniacryptid]

Lovely recipe for combining CSVs! This is helpful for me actually, I work in various CSVs all the time.

[github-actions]

✅ $10 OpenRouter API key sent to dakshatamishralakshya@gmail.com. Thanks for your contribution to the goose cookbook!