Flutter APK to AAB Conversion

I already have the full Flutter source code and a working APK; I now need it packaged as an Android App Bundle (AAB) so I can submit it to Google Play. The project sits on a standard configuration and relies on Flutter’s default libraries and plugins, so no environment-specific tweaks should be necessary. I am not requesting any feature additions or visual changes - this is purely a build-and-sign task.

What I will hand over:
• The complete source code that produced the current APK

What I expect back:
• A signed, upload-ready .aab file that passes Google Play Console checks
• A brief note (or README) listing the exact Flutter and Android SDK versions you used, plus the terminal command you executed, so I can reproduce the build later if needed

If you spot any issues while running Flutter build appbundle - such as warnings about version codes, minSdk, or manifest entries - please flag them before proceeding so we can keep the bundle compliant.