System Font Fallback

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Description

<-- A clear and concise description of what the problem is. -->

Steps To Reproduce

Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error ⚠️

Source .riv/.rev file

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Expected behavior

<-- A clear and concise description of what you expected to happen. -->

Screenshots

<-- If applicable, add screenshots to help explain your problem. -->

Device & Versions (please complete the following information)

• Device: [e.g. Android Emulator, iOS Simulator]
• OS: [e.g. Android SDK API Level 30, iOS 14.5]
• Flutter Version: Copy-paste the output of flutter --version
  e.g.:

Flutter 2.2.2 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 12a3456bc7 (2 eons ago) • 1970-01-01 08:56:01
Engine • revision 12a3456bc7
Tools • Dart 1.10.1

Additional context

<-- Add any other context about the problem here. -->

The issue contains only the standard report template and does not identify files, tests, entry points, reproduction steps, or expected behavior. Clarify the requested system font fallback behavior and provide a reproducible example before implementation work can be scoped.