[WIP] Resize columns, smart defaults

[Copilot]

• Analyze the feature request requirements
• Create technical specification document for column resize implementation
• Document smart column width defaults (Timestamp/Level fit content, Message expands)
• Document drag-resize functionality
• Document column configuration UI in settings
• Add implementation examples and code patterns
• Create step-by-step implementation guide with complete code examples
• Add quick reference guide for developers
• Create UI mockups showing visual design
• Update README with links to documentation

Original prompt

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This section details on the original issue you should resolve

<issue_title>Resize columns, smart defaults</issue_title>
<issue_description>Is your feature request related to a problem? Please describe.
If I don't have a lot of extra columns, I end up with Timestamp and Level being super wide despite not needing that much space.

Describe the solution you'd like

• Columns should be drag-resizable
• by default Message should expand to fill available space and Timestamp/level should only fit their content
• bonus if the Columns settings popup let you configure other columns to also expand/contract

Additional context

(would be happy to make a PR for this too if you want to share the source)</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #3

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[thedangander]

Ignore this PR - copilot can't cope with public issues and private repos!