refactor: improve code quality and error handling

[aritra0342]

• Remove redundant .clone().clone() in time_column.rs
• Avoid unnecessary Option clone in data_format.rs error message
• Replace .unwrap() with proper error handling in value.rs
• Add documentation to parse_pathway_pointer function

These changes improve code clarity and safety without changing behavior.

Introduction

To contribute code to the Pathway project, start by discussing your proposed changes on Discord or by filing an issue.
Once approved, follow the fork + pull request model against the main branch, ensuring you've signed the contributor license agreement.

Context

How has this been tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature or improvement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issue(s):

Checklist:

• My code follows the code style of this project,
• My change requires a change to the documentation,
• I described the modification in the CHANGELOG.md file.