refactor: manifest迁移到ota/文件夹

- ota/manifest.json (stable)
- ota/manifest-beta.json
- ota/manifest-nightly.json
- MainActivity URL更新为ota/路径

packages/client-android/android/app/src/main/java/dev/yuzu/gca/MainActivity.kt

@@ -101,7 +101,7 @@ class MainActivity : AppCompatActivity() {
     }
 
     private fun manifestUrl(channel: String): String {
-        val base = "https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/raw/branch/main/packages/client-android"
+        val base = "https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/raw/branch/main/ota"
         return when (channel) {
             "beta" -> "$base/manifest-beta.json"
             "nightly" -> "$base/manifest-nightly.json"

packages/client-android/manifest-beta.json

@@ -1 +0,0 @@
-{"version":"0.1.0","builds":{"android":{"type":"apk","tag":"v0.1.0-dav-android-7","url":"https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk","sha256":"6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6","size":3223411,"channel":"beta"}}}

packages/client-android/manifest-nightly.json

@@ -1 +0,0 @@
-{"version":"0.1.0","builds":{"android":{"type":"apk","tag":"v0.1.0-dav-android-7","url":"https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk","sha256":"6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6","size":3223411,"channel":"nightly"}}}

packages/client-android/manifest.json

@@ -1,14 +0,0 @@
-{
-  "version": "0.1.0",
-  "builds": {
-    "android": {
-      "type": "apk",
-      "tag": "v0.1.0-dav-android-7",
-      "url": "https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk",
-      "sha256": "6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6",
-      "size": 3223411,
-      "channel": "stable",
-      "minVersion": "0.1.0"
-    }
-  }
-}