[BUG] Google 2-Step Verification prompt does not appear on Huawei -hw builds

**Describe the bug**
Google 2-Step Verification prompt does not appear on Huawei `-hw` builds of microG Services.

When Google asks me to confirm a sign-in on my phone, the device often does not show any visible confirmation prompt or notification, so I cannot approve the sign-in from this Huawei device.

**To Reproduce**
Steps to reproduce the behavior:
1. Install the Huawei `-hw` builds of GmsCore and Vending companion.
2. Add a Google account in microG.
3. Enable Google 2-Step Verification prompt for the account.
4. Try to sign in to the same Google account from another device or browser.
5. Choose the option that sends a confirmation prompt to the phone.
6. The Huawei device does not show a visible prompt / confirmation notification.

**Expected behavior**
microG should show a visible Google 2-Step Verification confirmation prompt or notification, allowing the user to approve or deny the sign-in.

**Screenshots**
Not available right now.

**System**
Android Version: 12
Device: Huawei / Tianyi TYH641M
Custom ROM: Stock Huawei / HarmonyOS-based system

microG / package versions tested:

- `com.google.android.gms`
- Version: `0.3.15.250932-hw`
- Version code: `250932030`

- `com.android.vending`
- Version: `0.3.15.40226-hw`
- Version code: `84022630`

**Additional context**
Huawei’s signature compatibility layer appears to depend on the original release signing certificate. On this device, the old official `-hw` packages are recognized by Huawei and the system binds:

`com.google.android.gms/com.huawei.signature.diff.SignatureService`

`com.android.vending/com.huawei.signature.diff.SignatureService`

The recognized package signing certificate SHA-1 is:

`10321bd893f69af97f7573aafe9de1dc0901f3a1`

With locally rebuilt dirty/debug APKs, the package signing certificate changes. Even though the APK still contains `com.huawei.signature.diff.SignatureService`, Huawei no longer recognizes the package in the same way, and the signature compatibility layer breaks. This makes it difficult to test prompt-related fixes locally unless an official signed Huawei `-hw` build is provided.

While inspecting the prompt receiver path, possible causes may include nested prompt payload handling or prompt state being marked complete/read before the user can interact with it.

I am not asking for the private signing key. I am requesting either an official signed `-hw` test build with a fix, or guidance on how this can be tested without breaking Huawei’s signature compatibility mechanism.

Start by tracing the prompt receiver path and the Huawei SignatureService bindings for com.google.android.gms and com.android.vending. Reproduce with an official signed Huawei -hw build, since locally rebuilt APKs break Huawei's signature compatibility. Done means a visible 2-Step Verification prompt or notification appears and allows approval or denial.

Written by the indexing model from the issue text.