refactor: use plaintext Gitea URL instead of XOR+Base64 scramble

- Gitea URL hardcoded as GITEA_API constant (no more release-notes discovery)
- Removed parseUpdateSource / unscramble / SCRAMBLE_KEY
- Release notes no longer need update-source comment
- version 1.9.4 -> 1.9.5 (code 33 -> 34)

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

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

@@ -70,19 +70,15 @@ class UpdateChecker(private val context: Context) {
             val now = System.currentTimeMillis()
             if (throttle && now - settings.lastUpdateCheckTime.value < CHECK_INTERVAL_MS) return@runCatching updateInfo.value
 
-            // 先查 GitHub（公开默认源），从其 release notes 动态发现额外源（如自建 Gitea），取最高版本
+            // 双源查询：Gitea（国内优先）+ GitHub（备用），取最高版本
             // 同版本时 Gitea 优先（国内可达，GitHub 可能被墙导致下载失败）
             val infos = mutableListOf<UpdateInfo>()
             var ghInfo: UpdateInfo? = null
             var giteaInfo: UpdateInfo? = null
-            val gh = runCatching { fetchRelease(GITHUB_API) }.getOrNull()
-            if (gh != null) {
-                ghInfo = gh
-                giteaInfo = parseUpdateSource(gh.releaseNotes)?.let { runCatching { fetchRelease(it) }.getOrNull() }
-                // Gitea 放前面，同版本时优先用它下载（国内可达）
-                if (giteaInfo != null) infos.add(giteaInfo)
-                infos.add(gh)
-            }
+            giteaInfo = runCatching { fetchRelease(GITEA_API) }.getOrNull()
+            if (giteaInfo != null) infos.add(giteaInfo)
+            ghInfo = runCatching { fetchRelease(GITHUB_API) }.getOrNull()
+            if (ghInfo != null) infos.add(ghInfo)
             settings.setLastUpdateCheck(now)
             if (infos.isEmpty()) {
                 lastError.value = "所有更新源不可达"
@@ -303,26 +299,10 @@ class UpdateChecker(private val context: Context) {
         return false
     }
 
-    /** 从 release notes 的 HTML 注释里解析额外更新源（加扰编码，兼容 Base64/明文）。 */
-    private fun parseUpdateSource(body: String): String? {
-        val raw = Regex("""update-source:\s*(\S+)""").find(body)?.groupValues?.getOrNull(1) ?: return null
-        // 加扰格式：Base64(反转(XOR(明文, key)))。尝试完整解扰，失败则依次尝试 Base64/明文。
-        val b64 = runCatching { java.util.Base64.getDecoder().decode(raw) }.getOrNull() ?: return raw
-        val unscrambled = unscramble(b64)
-        return unscrambled ?: runCatching { String(b64, Charsets.UTF_8) }.getOrNull() ?: raw
-    }
-
-    /** 解扰：反转字节 → XOR 每字节 → UTF-8 字符串。 */
-    private fun unscramble(data: ByteArray): String? = runCatching {
-        val key = SCRAMBLE_KEY
-        val reversed = data.reversedArray()
-        String(ByteArray(reversed.size) { i -> ((reversed[i].toInt() and 0xFF) xor (key[i % key.size].toInt() and 0xFF)).toByte() }, Charsets.UTF_8)
-    }.getOrNull()
-
     companion object {
         const val GITHUB_API = "https://api.github.com/repos/lsxf/a2i/releases/latest"
+        const val GITEA_API = "https://gitea.songer.eu.org/api/v1/repos/song/a2i/releases/latest"
         const val CHECK_INTERVAL_MS = 24L * 60 * 60 * 1000
-        private val SCRAMBLE_KEY = byteArrayOf(0x4B, 0x6F, 0x72, 0x6E)  // "Korn"
     }
 
     fun formatSize(bytes: Long): String {