Drop -v26 qualifier from mipmap-anydpi (minSdk is 26)

[driversti]

Problem

`app/src/main/res/mipmap-anydpi-v26/` has the `-v26` qualifier, but the project's `minSdk = 26`, so the qualifier is redundant. Lint surfaces it as:

```
Warning: This folder configuration (v26) is unnecessary; minSdkVersion is 26. Merge all the resources in this folder into mipmap-anydpi. [ObsoleteSdkInt]
```

Suggested fix

Rename `app/src/main/res/mipmap-anydpi-v26/` → `app/src/main/res/mipmap-anydpi/`. Contents stay as-is (two `adaptive-icon` XMLs: `ic_launcher.xml`, `ic_launcher_round.xml`).

Acceptance

• Folder renamed, both files still present.
• `./gradlew :app:assembleDebug` passes.
• The launcher icon still renders correctly on install.
• Lint no longer reports `ObsoleteSdkInt` on this folder.