fix: reduce TODO.md merge conflicts during rebases with gitattributes

[Copilot]

TODO.md creates merge conflicts on every commit during rebases because line numbers change as code moves. Since the file is auto-generated by the pre-commit hook after each commit anyway, these conflicts are unnecessary noise.

Changes

• .gitattributes: Configure merge=union strategy for TODO.md — combines lines from both versions instead of conflicting, letting the hook regenerate the correct state
• README.md: Document the solution in Troubleshooting for users experiencing this in their own repos

Usage

Add to your repository's .gitattributes:

TODO.md merge=union

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Too many merge conflicts</issue_title>
<issue_description>When rebasing branches, TODO.md file creates a merge conflict for each commit, causing too many merge conflicts that often affect only the TODO.md file.</issue_description>

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

• Fixes Too many merge conflicts #179

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[simone-viozzi]

superseed by #197