fix: startup always checks + dual-source (Gitea+GitHub) take highest

- start(): check on every launch (no 24h throttle) so the banner shows
  after restart even if checked manually moments ago; plus a 24h loop
  while app is resident
- check both Gitea and GitHub release APIs, skip whichever is
  unreachable, notify the higher version
- version 1.7.2 -> 1.7.3 (code 15 -> 16)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/com/a2i/forwarder/core/UpdateChecker.kt

@@ -11,6 +11,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import okhttp3.OkHttpClient
@@ -49,51 +50,71 @@ class UpdateChecker(private val context: Context) {
     fun start() {
         scope.launch {
             delay(5000)  // 启动 5 秒后首检，给网络/应用初始化留时间
-            check(force = false)
+            doCheck(throttle = false, toggle = true)  // 启动必查（无视节流，但尊重开关）
+            while (isActive) {
+                delay(CHECK_INTERVAL_MS)  // 常驻期间每 24h 巡检一次
+                doCheck(throttle = true, toggle = true)
+            }
         }
     }
 
-    suspend fun check(force: Boolean): Result<UpdateInfo?> = withContext(Dispatchers.IO) {
+    /** 手动检查：无视节流和开关（用户主动）。 */
+    suspend fun check(force: Boolean): Result<UpdateInfo?> = doCheck(throttle = !force, toggle = !force)
+
+    private suspend fun doCheck(throttle: Boolean, toggle: Boolean): Result<UpdateInfo?> = withContext(Dispatchers.IO) {
         runCatching {
             val settings = app.settings
+            if (toggle && !settings.updateCheckEnabled.value) return@runCatching updateInfo.value
             val now = System.currentTimeMillis()
-            // 自动检查跳过条件（仅 force=false 时有效）
-            if (!force) {
-                if (!settings.updateCheckEnabled.value) return@runCatching updateInfo.value
-                if (now - settings.lastUpdateCheckTime.value < CHECK_INTERVAL_MS) return@runCatching updateInfo.value
-            }
-            val req = Request.Builder()
-                .url(RELEASES_API)
-                .header("Accept", "application/json")
-                .header("User-Agent", "a2i-android")
-                .get()
-                .build()
-            val info = http.newCall(req).execute().use { res ->
-                if (!res.isSuccessful) error("HTTP ${res.code}")
-                val body = res.body?.string() ?: error("空响应")
-                parseRelease(body)
+            if (throttle && now - settings.lastUpdateCheckTime.value < CHECK_INTERVAL_MS) return@runCatching updateInfo.value
+
+            // 双源查询（Gitea 国内优先 + GitHub 备用），任一不通跳过，取最高版本
+            val infos = RELEASES_APIS.mapNotNull { api ->
+                runCatching { fetchRelease(api) }.getOrNull()
             }
             settings.setLastUpdateCheck(now)
+            if (infos.isEmpty()) {
+                lastError.value = "所有更新源不可达"
+                return@runCatching updateInfo.value
+            }
             val current = currentVersionName()
-            val available = info != null &&
-                isNewer(info.latestVersion, current) &&
-                info.latestVersion != settings.ignoredVersion.value
+            val best = infos
+                .filter { isNewer(it.latestVersion, current) && it.latestVersion != settings.ignoredVersion.value }
+                .maxByOrNull { versionKey(it.latestVersion) }
             val prev = updateInfo.value
-            updateInfo.value = if (available) info else {
-                lastNotifiedVersion = null  // 清除记录，等下一个新版
-                null
+            if (best == null) {
+                updateInfo.value = null
+                lastNotifiedVersion = null
+            } else {
+                updateInfo.value = best
             }
             lastError.value = null
 
             // 发现新版且之前没推过通知 → 自动推送到所有已开启通道
-            if (available && info != null && info.latestVersion != lastNotifiedVersion) {
-                lastNotifiedVersion = info.latestVersion
-                notifyNewVersion(prev, info)
+            if (best != null && best.latestVersion != lastNotifiedVersion) {
+                lastNotifiedVersion = best.latestVersion
+                notifyNewVersion(prev, best)
             }
             updateInfo.value
         }.onFailure { lastError.value = it.message ?: "检查失败" }
     }
 
+    private fun fetchRelease(api: String): UpdateInfo? {
+        val req = Request.Builder()
+            .url(api)
+            .header("Accept", "application/json")
+            .header("User-Agent", "a2i-android")
+            .get()
+            .build()
+        return http.newCall(req).execute().use { res ->
+            if (!res.isSuccessful) error("HTTP ${res.code}")
+            parseRelease(res.body?.string() ?: error("空响应"))
+        }
+    }
+
+    private fun versionKey(v: String): String =
+        v.split(".").joinToString(".") { (it.substringBefore("-").toIntOrNull() ?: 0).toString().padStart(4, '0') }
+
     /** 发现新版后，自动通过所有已开启的推送通道通知用户 */
     private fun notifyNewVersion(prev: UpdateInfo?, info: UpdateInfo) {
         val s = app.settings
@@ -225,7 +246,11 @@ class UpdateChecker(private val context: Context) {
     }
 
     companion object {
-        const val RELEASES_API = "https://UPDATE_SOURCE_HIDDEN/api/v1/repos/song/a2i/releases/latest"
+        // 双源：Gitea（国内优先）+ GitHub（备用），任一不通跳过，取最高版本
+        val RELEASES_APIS = listOf(
+            "https://UPDATE_SOURCE_HIDDEN/api/v1/repos/song/a2i/releases/latest",
+            "https://api.github.com/repos/lsxf/a2i/releases/latest",
+        )
         const val CHECK_INTERVAL_MS = 24L * 60 * 60 * 1000
     }