build(release): build the release APK for ARM only (arm64-v8a + armeabi-v7a)

Adds ndk.abiFilters = ["arm64-v8a", "armeabi-v7a"] to the release build
type only, so the release APK/AAB ship the two ARM ABIs (64-bit + 32-bit)
instead of a universal build. x86 and x86_64 are intentionally dropped.
defaultConfig and the debug type are left untouched: CI's E2E matrix runs
the debug build on x86_64 emulators and needs the x86_64 native libs
(incl. libsqlcipher.so).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/build.gradle.kts

@@ -88,6 +88,14 @@ android {
             } else {
                 signingConfigs.getByName("debug")
             }
+            // Ship ARM only — arm64-v8a (64-bit) + armeabi-v7a (32-bit); x86/x86_64 are
+            // intentionally dropped. Scoped to this build type ONLY — do NOT move to defaultConfig
+            // or the debug type: CI's E2E matrix runs the debug build on x86_64 emulators
+            // (.github/workflows/ci.yml) and needs the x86_64 native libs (incl. libsqlcipher.so).
+            // See docs/play-compliance.md and docs/fdroid-compliance.md for the coverage tradeoff.
+            ndk {
+                abiFilters += listOf("arm64-v8a", "armeabi-v7a")
+            }
         }
     }