fix(nutrition): resolve fl_chart app crash when toggling meal details in Nutritional Plan Detail screen

[pankaj-basnet]

🧩 The Problem

When a user toggles the meal details view (_toggleDetails in meal.dart) on a meal that has no logged entries today but contains a planned macro goal, the application crashes with an unhandled exception:
Unsupported operation: Infinity or NaN toInt

This occurs because MealDiaryBarChartWidget maps target and actual calorie values straight into percentages to render BarChartRodData. If widget._logged.energy (or any other macro) evaluates to 0, Dart handles the calculation as Infinity. When the underlying fl_chart package attempts to paint the background grid lines and axis intervals, it attempts to convert this infinity value to an integer (~/), resulting in a hard crash on the canvas layer.

🛠️ The Fix

Instead of passing raw mathematical division results directly to the chart data structures, this PR introduces a safePercent helper method inside lib/widgets/nutrition/charts.dart.

The helper safely sanitizes inputs before they ever reach fl_chart:

• Returns 0.0 immediately if the planned/logged target value is less than or equal to 0.
• Adds explicit logic guards checking for .isNaN and .isInfinite anomalies to ensure unexpected data states output a clean, non-breaking 0% bar representation.

Related Issue(s)

• Closes App crashes when 'meal details' toggles in Nutritional Plan Detail screen if zero planned/logged values #1201

Test

Added a comprehensive widget test suite (test/nutrition/nutritional_meal_charts_test.dart) to ensure the chart renders safely under the following conditions:

• Valid data inputs.
• Logged meal data resolving to zero.
• Planned macro data resolving to zero.
• Both logged and planned data resolving to zero simultaneously.

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Set a 100-character limit to avoid white space diffs (run dart format .)

📱 UI Changes & Verification

1. Empty State (No Meals)	2. Logging a New Meal	3. Meal Details View

[rolandgeider]

thanks!