Feat/radar max value config

[artsooter]

hello ，This PR is aims to add this feature in https://github.com/imaNNeo/fl_chart/issues/2002

Problem background

We encountered two problems in the issue.

• How to set the maximum value of the Radar Chart to a specified value.
• How to display the maximum tick value on the chart.

Solution

This PR introduces two new parameters to RadarChartData:

1. maxValue Parameter

RadarChartData( dataSets: myDataSets, maxValue: 100.0, // Set custom maximum value )

• Type: double? (optional)
• Default: null (uses data maximum)
• Purpose: Allows setting a custom maximum value instead of calculating from data

2. showMaxTick Parameter

RadarChartData( dataSets: myDataSets, showMaxTick: true, // Show maximum tick value )

• Type: bool
• Default: false (preserves existing behavior)
• Purpose: Controls whether the maximum tick is displayed on the chart

Result

[imaNNeo]

Hi, thanks for your great contribution! I have some points to mention.

1. I think instead of having a showMaxTick, we can have a checkToShowTick resolver that the user can decide to show which ticks (it can be like a callback, like checkToShowDot in LineChartData). This way, we can hide the max entry by default (to be backward compatible), also it adds a lot of customizability for other use cases.
2. I like the change for the maxValue property, thanks a lot. I was thinking to have something for minValue as well (but not for now, let's keep this PR as simple as possible). But if you found time in the future, I would appreciate if you add the minValue as well to keep the consistency.
3. Please add the newly added property in the radar_chart.md file.

Then we're good to go!

[artshooter]

Hello , I sincerely apologize for the inconvenience, but the author account of this PR has been retired and can no longer be used.

Therefore, I have submitted a new PR using my new account, which implements the features based on the feedback. https://github.com/imaNNeo/fl_chart/pull/2025

Thank you.