feat: check for updates page in settings

Add a full-screen update checker accessible from a button at the
bottom of the settings page. It queries the fork's GitHub latest
release and can download + install the APK in place.

- UpdateRepository (core/data): fetch releases/latest via GitHub API,
  parse tag/description/APK asset, stream APK download to cacheDir
- VersionComparator (core/domain): compare 4.4.6-ba7opf.N style tags
  (base version first, then build number; v-prefix tolerant) + tests
- IMainContainer/MainContainer: inject updateRepo
- UpdateCheckerScreen (feature/settings): shows current version,
  checks for updates, displays latest version + release notes, and a
  Download & install button; FileProvider hands the APK to the
  system installer
- SettingsScreen: bottom entry button, full-screen page toggle
- AndroidManifest: REQUEST_INSTALL_PACKAGES permission + FileProvider
- i18n strings (en/zh)

core/data/src/main/java/com/rtbishop/look4sat/core/data/injection/MainContainer.kt

@@ -35,6 +35,7 @@ import com.rtbishop.look4sat.core.data.repository.SatelliteRepo
 import com.rtbishop.look4sat.core.data.repository.SelectionRepo
 import com.rtbishop.look4sat.core.data.repository.SensorsRepo
 import com.rtbishop.look4sat.core.data.repository.SettingsRepo
+import com.rtbishop.look4sat.core.data.repository.UpdateRepository
 import com.rtbishop.look4sat.core.data.source.LocalSource
 import com.rtbishop.look4sat.core.data.source.RemoteSource
 import com.rtbishop.look4sat.core.data.usecase.AddToCalendar
@@ -79,6 +80,7 @@ class MainContainer(private val context: Context) : IMainContainer {
     override val satelliteRepo = provideSatelliteRepo()
     override val databaseRepo = provideDatabaseRepo()
     override val amSatRepo by lazy { AmSatRepository(remoteSource, appScope) }
+    override val updateRepo by lazy { UpdateRepository(remoteSource) }
     override val radioTrackingService: IRadioTrackingService by lazy {
         val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
         RadioTrackingService(appScope, manager, satelliteRepo, settingsRepo)

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/UpdateRepository.kt

@@ -0,0 +1,67 @@
+package com.rtbishop.look4sat.core.data.repository
+
+import com.rtbishop.look4sat.core.domain.model.LatestRelease
+import com.rtbishop.look4sat.core.domain.repository.IUpdateRepository
+import com.rtbishop.look4sat.core.domain.source.IRemoteSource
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import org.json.JSONObject
+import java.io.File
+
+class UpdateRepository(
+    private val remoteSource: IRemoteSource
+) : IUpdateRepository {
+
+    override suspend fun getLatestRelease(): LatestRelease? = withContext(Dispatchers.IO) {
+        val result = remoteSource.getNetworkStream(LATEST_RELEASE_URL)
+        val stream = result.stream ?: return@withContext null
+        try {
+            val json = stream.bufferedReader().use { it.readText() }
+            parseRelease(json)
+        } catch (e: Exception) {
+            println("UpdateRepository parse failure: $e")
+            null
+        }
+    }
+
+    override suspend fun downloadApk(url: String, dest: File): Boolean = withContext(Dispatchers.IO) {
+        if (url.isBlank()) return@withContext false
+        val result = remoteSource.getNetworkStream(url)
+        val stream = result.stream ?: return@withContext false
+        try {
+            dest.outputStream().use { out -> stream.use { it.copyTo(out) } }
+            true
+        } catch (e: Exception) {
+            println("UpdateRepository download failure: $e")
+            false
+        }
+    }
+
+    private fun parseRelease(json: String): LatestRelease? {
+        val obj = JSONObject(json)
+        val tag = obj.optString("tag_name")
+        if (tag.isBlank()) return null
+        val assets = obj.optJSONArray("assets")
+        var apkUrl: String? = null
+        if (assets != null) {
+            for (i in 0 until assets.length()) {
+                val asset = assets.optJSONObject(i) ?: continue
+                val name = asset.optString("name", "")
+                if (name.endsWith(".apk")) {
+                    apkUrl = asset.optString("browser_download_url", "").ifBlank { null }
+                    if (apkUrl != null) break
+                }
+            }
+        }
+        return LatestRelease(
+            versionTag = tag,
+            title = obj.optString("name", ""),
+            body = obj.optString("body", ""),
+            apkUrl = apkUrl
+        )
+    }
+
+    private companion object {
+        const val LATEST_RELEASE_URL = "https://api.github.com/repos/atsunatsu/Look4Sat/releases/latest"
+    }
+}