fix: drop armeabi-v7a ABI filter now that the CW module is gone

The ndk abiFilters restriction was added in a333192 ("feat: add CW
decoder and linear calculator page") to accommodate Morse Expert's
32-bit-only libnativedecoderjni.so. Upstream app/build.gradle.kts
contains only the plugins block, so this is fork-specific.

With feature/cw removed, the filter no longer has a reason to exist and
it kept the app 32-bit only — which Google Play has rejected since
2019-08 (64-bit requirement).

Verified after the change:
- ./gradlew assembleDebug -> BUILD SUCCESSFUL
- APK now ships arm64-v8a, armeabi-v7a, x86, x86_64
  (the only remaining .so is androidx.graphics.path, 7 KB)
- ./gradlew test -> 82 tests, 0 failures

app/build.gradle.kts

@@ -6,7 +6,6 @@ android {
     namespace = libs.versions.packageName.get()
     defaultConfig {
         applicationId = "cn.ba7opf.look4sat"
-        ndk { abiFilters.add("armeabi-v7a") }
     }
     signingConfigs {
         create("release") {