feat: add maxValue and checkToShowTick in radarChart

[artshooter]

Summary

This PR implements the customization features for RadarChart as discussed in #2002.

Note: This is a follow-up to PR #2007. The previous PR was submitted from the GitHub account artsooter, which is no longer available.
I've created this new PR with a fresh account to implement the feedback.

Changes

1. maxValue parameter: Allows setting a custom maximum value for the RadarChart instead of auto-calculating from data.

2. checkToShowTick callback: Implemented as suggested in the review. This function determines which ticks should be displayed by receiving the tick
   index, and list of all ticks. Returns a boolean to control visibility. Default behavior shows all ticks except the last one.

3. Documentation: Added descriptions for both parameters to radar_chart.md.

Documentation

PropName	Description	default value
maxValue	Defines a custom maximum value for the [RadarChart]. If provided, this value will be used instead of the automatically calculated maximum from the data.	null
checkToShowTick	Determines which ticks should be displayed on the [RadarChart]. By default, shows all ticks except the last one.	showTickWithoutLast

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[Copilot]

Pull request overview

This PR adds two new customization features to RadarChart: a maxValue parameter to set a custom maximum value for the chart instead of auto-calculating from data, and a checkToShowTick callback to control which tick labels are displayed. This addresses issue #2002 where users wanted to set specific max values (like 100) and control tick visibility. The implementation follows fl_chart's established patterns for callback-based customization, similar to checkToShowHorizontalLine in axis charts.

Changes:

• Added maxValue parameter to RadarChartData with validation for finite numbers
• Added checkToShowTick callback with default behavior to hide the last tick
• Updated documentation to describe both new parameters

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
lib/src/chart/radar_chart/radar_chart_data.dart	Added maxValue field and checkToShowTick callback with proper equality, copyWith, and lerp support
lib/src/chart/radar_chart/radar_chart_painter.dart	Modified tick rendering to use checkToShowTick callback for label visibility and updated iteration to include all ticks
test/chart/radar_chart/radar_chart_data_test.dart	Added comprehensive tests for maxValue functionality (null, custom, validation) and checkToShowTick (equality, copyWith)
repo_files/documentations/radar_chart.md	Documented maxValue and checkToShowTick parameters with descriptions and defaults

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[Copilot]

The tick line drawing is hardcoded to skip the last tick (index != ticks.length - 1), while the tick label drawing is controlled by the checkToShowTick callback. This creates an inconsistency where:

1. If a user wants to show the last tick label via checkToShowTick, the tick line won't be drawn
2. The tick line visibility is not user-controllable

Consider using checkToShowTick to control BOTH the tick line and label drawing, or add a separate callback for tick lines if independent control is needed. The current implementation limits the flexibility that checkToShowTick is supposed to provide.

Suggested change

	if (index != ticks.length - 1) {
	if (data.radarShape == RadarShape.circle) {
	canvasWrapper.drawCircle(centerOffset, tickRadius, _tickPaint);
	} else {
	canvasWrapper.drawPath(
	_generatePolygonPath(
	centerX,
	centerY,
	tickRadius,
	data.titleCount,
	),
	_tickPaint,
	);
	}
	}
	if (!data.checkToShowTick(index, ticks)) return;
	final showTick = data.checkToShowTick(index, ticks);
	if (!showTick) {
	return;
	}
	if (data.radarShape == RadarShape.circle) {
	canvasWrapper.drawCircle(centerOffset, tickRadius, _tickPaint);
	} else {
	canvasWrapper.drawPath(
	_generatePolygonPath(
	centerX,
	centerY,
	tickRadius,
	data.titleCount,
	),
	_tickPaint,
	);
	}