[WIP] Add graph plotting feature for daily data visualization

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Repository: daedalus/agp_tool

Goal
Add a graph plotting feature that plots each day as a separate line, with each line in a different color.

Requirements

• Implement plotting so that data is grouped by day and rendered as multiple lines on the same graph.
• Ensure each day’s line uses a distinct color (use an existing palette/cycler if available in the project’s plotting stack).
• Integrate the graph into the existing CLI/tool workflow so users can generate the plot from current output/data.
• Update/extend tests if the repo has a test suite; otherwise add minimal verification or example output.
• Update documentation/README with usage instructions and an example (if appropriate).

Constraints

• Open a pull request against the master branch.

Context

• Repo URL: https://github.com/daedalus/agp_tool

Acceptance Criteria

• Running the tool with the plotting option produces a graph where each day is a separate colored line.
• Plot legend or labeling makes it clear which line corresponds to which day.
• Code follows existing project style and passes existing CI/tests.

This pull request was created from Copilot chat.

---

💡 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.