Add columns-3-cog icon

[irvineacosta]

What is the purpose of this pull request?

• [x] New Icon
• [ ] Bug fix
• [ ] New Feature
• [ ] Documentation update
• [ ] Other:

Description

This PR adds a new columns-cog icon, which is a settings/editing variant of the existing columns-3 icon. The design follows Lucide’s existing conventions for settings-related icons by combining columns-3 with a cog element, similar to how other icons represent customization or configuration.

Icon use case

This icon is useful for:

• Customizing table columns in UI settings panels.
• Editing column layouts in grid-based design tools.
• Adjusting column preferences in dashboards or data tables.

Alternative icon designs

• No significant alternatives were considered, as this design follows Lucide’s cog-based settings icons.

Icon Design Checklist

Concept

• [x] I have provided valid use cases for each icon.
• [x] I have not added any brand or logo icon.
• [x] I have not used any hate symbols.
• [x] I have not included any religious or political imagery.

Author, credits & license

• [x] The icons are solely my own creation.
• [ ] The icons were originally created in #<issueNumber> by @<githubUser>
• [x] I've based them on the existing columns-3 and the cog element used in other Lucide icons.
• [ ] I've based them on the following design:

Naming

• [x] I've read and followed the naming conventions.
• [x] I've named the icon by what it is rather than its use case.
• [x] I've provided a meta JSON file in icons/columns-cog.json.

Design

• [x] I've read and followed the icon design guidelines.
• [x] I've made sure that the icon looks sharp on low DPI displays.
• [x] I've made sure that the icon looks consistent with the icon set in size, optical volume, and density.
• [x] I've made sure that the icon is visually centered.
• [x] I've correctly optimized all icons to three points of precision.

Before Submitting

• [x] I've read the Contribution Guidelines.
• [x] I've checked if there was an existing PR that solves the same issue.