Run/debug gutter icon missing for main()/tests in Flutter projects, reproduces on fresh projects, persists across full config wipe and new project

macOS version: Tahoe 26.6.1
Hardware: MacBook Air 15" M4, 16GB RAM
Android Studio version: Android Studio Quail 3 | 2026.1.3 Patch 1
Flutter plugin version: 95.0.0
Dart plugin version: 508.0.0
Flutter SDK version: 3.47.0

The run/debug gutter icon (the icon next to main() and test functions used to run/debug directly from the gutter) does not appear in Flutter projects. Other gutter icons (breakpoints, VCS markers) render normally. Clicking in the gutter where the run icon should be sets a breakpoint instead of showing a run/debug option — the line marker for run/debug is not being registered at all, not just failing to render visually.

Troubleshooting already attempted (issue persists through all of these):

- Full "Restore Default Settings" in Android Studio
- Complete manual deletion of ~/Library/Application Support/JetBrains, ~/Library/Caches/JetBrains, ~/Library/Logs/JetBrains, and equivalents for Android Studio, followed by clean reinstall
- Reinstalled IntelliJ IDEA Ultimate — same issue reproduces
- Upgraded Flutter SDK to the latest version
- Confirmed Dart Analysis Server shows no errors and is running
- Confirmed Flutter/Dart SDK paths are valid in IDE settings
- Ran flutter pub get and flutter doctor -v with no issues reported
- Tested with a completely new, empty Flutter project — same issue

Reproduce the missing gutter action at main() and test functions in a fresh Flutter project using the Flutter and Dart plugin integration. Start by tracing how the run/debug gutter marker is registered, then verify that it appears and launches run or debug actions without interfering with breakpoints; confirm behavior after flutter pub get and with Dart Analysis Server running.

Written by the indexing model from the issue text.