build(android): add --device/--abi to build only the needed architecture

An on-device test build compiled all four ABIs (arm64/arm/x86/x86_64),
so three of the four Rust compiles were thrown away. That dominated the
build time when iterating against a connected phone.

--device resolves the attached device's ABI via adb and targets just
that triple; --abi <target> selects one explicitly; ABI= works as an
env var. Default behaviour is unchanged (all four), since a
distributable universal APK genuinely needs them.

  bun run android:build:device
  bun run android:build:release:device

package.json

@@ -1,6 +1,6 @@
 {
   "name": "jellytau",
-  "version": "0.2.1",
+  "version": "0.2.2",
   "description": "",
   "type": "module",
   "packageManager": "bun@1.3.5",
@@ -20,6 +20,8 @@
     "check:boundary": "bash scripts/check-frontend-boundary.sh",
     "android:build": "./scripts/build-android.sh",
     "android:build:release": "./scripts/build-android.sh release",
+    "android:build:device": "./scripts/build-android.sh --device",
+    "android:build:release:device": "./scripts/build-android.sh release --device",
     "android:build:clean": "rm -rf node_modules/.vite dist .svelte-kit .next build target src-tauri/target && bun install && bun run build",
     "android:deploy": "./scripts/deploy-android.sh",
     "android:dev": "./scripts/build-and-deploy.sh",