feat(android): add youtube_via_relay toggle to Advanced settings

Expose the `youtube_via_relay` config flag in the Android UI, matching
the desktop checkbox. Adds the field to MhrvConfig with serialization
round-trip (toJson / loadFromJson / encode), a Switch in the Advanced
section, and EN + FA string resources.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/therealaleph/mhrv/ConfigStore.kt

@@ -135,6 +135,13 @@ data class MhrvConfig(
     /** Package names used by ONLY and EXCEPT. Empty under ALL. */
     val splitApps: List<String> = emptyList(),
 
+    /**
+     * Route YouTube traffic through Apps Script relay instead of the
+     * SNI-rewrite tunnel. Avoids Google SafeSearch-on-SNI / restricted
+     * mode, but slower for video. Maps to Rust `youtube_via_relay`.
+     */
+    val youtubeViaRelay: Boolean = false,
+
     /** UI language toggle. Non-Rust; honoured only by the Android wrapper. */
     val uiLang: UiLang = UiLang.AUTO,
 ) {
@@ -212,6 +219,7 @@ data class MhrvConfig(
                 put("passthrough_hosts", JSONArray().apply { passthroughHosts.forEach { put(it) } })
             }
             if (tunnelDoh) put("tunnel_doh", true)
+            if (youtubeViaRelay) put("youtube_via_relay", true)
             // Trim/drop-empty/dedupe before serializing — symmetric with the
             // read-side normalization in loadFromJson(), so a user typing
             // " doh.foo " or accidentally adding a duplicate doesn't end up
@@ -317,6 +325,7 @@ object ConfigStore {
         if (cfg.upstreamSocks5.isNotBlank()) obj.put("upstream_socks5", cfg.upstreamSocks5)
         if (cfg.passthroughHosts.isNotEmpty()) obj.put("passthrough_hosts", JSONArray().apply { cfg.passthroughHosts.forEach { put(it) } })
         if (cfg.tunnelDoh != defaults.tunnelDoh) obj.put("tunnel_doh", cfg.tunnelDoh)
+        if (cfg.youtubeViaRelay != defaults.youtubeViaRelay) obj.put("youtube_via_relay", cfg.youtubeViaRelay)
         val cleanBypassDohHosts = cfg.bypassDohHosts
             .map { it.trim() }
             .filter { it.isNotEmpty() }
@@ -420,6 +429,7 @@ object ConfigStore {
                 buildList { for (i in 0 until arr.length()) add(arr.optString(i)) }
             }?.filter { it.isNotBlank() }.orEmpty(),
             tunnelDoh = obj.optBoolean("tunnel_doh", false),
+            youtubeViaRelay = obj.optBoolean("youtube_via_relay", false),
             bypassDohHosts = obj.optJSONArray("bypass_doh_hosts")?.let { arr ->
                 buildList { for (i in 0 until arr.length()) add(arr.optString(i)) }
             }?.filter { it.isNotBlank() }.orEmpty(),

android/app/src/main/java/com/therealaleph/mhrv/ui/HomeScreen.kt

@@ -1196,6 +1196,25 @@ private fun AdvancedSettings(
             )
         }
 
+        // youtube_via_relay
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.fillMaxWidth(),
+        ) {
+            Column(modifier = Modifier.weight(1f)) {
+                Text(stringResource(R.string.adv_youtube_via_relay), style = MaterialTheme.typography.bodyMedium)
+                Text(
+                    stringResource(R.string.adv_youtube_via_relay_help),
+                    style = MaterialTheme.typography.labelSmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+            Switch(
+                checked = cfg.youtubeViaRelay,
+                onCheckedChange = { onChange(cfg.copy(youtubeViaRelay = it)) },
+            )
+        }
+
         // log_level dropdown
         var expanded by remember { mutableStateOf(false) }
         val levels = listOf("trace", "debug", "info", "warn", "error", "off")

android/app/src/main/res/values-fa/strings.xml

@@ -67,6 +67,8 @@
     <!-- Advanced section -->
     <string name="adv_verify_tls">بررسی TLS طرف مقابل</string>
     <string name="adv_verify_tls_help">خاموش کردن، بررسی گواهی را برای لبهٔ گوگل غیرفعال می‌کند. فقط برای اشکال‌زدایی کاربرد دارد.</string>
+    <string name="adv_youtube_via_relay">ارسال یوتیوب از طریق رله</string>
+    <string name="adv_youtube_via_relay_help">ترافیک youtube.com / youtu.be / ytimg.com را به‌جای تونل SNI-rewrite از رلهٔ Apps Script عبور می‌دهد. حالت محدود را دور می‌زند ولی پخش ویدیو کندتر می‌شود.</string>
     <string name="adv_log_level">log_level</string>
     <string name="adv_parallel_relay">parallel_relay: %1$d</string>
     <string name="adv_parallel_relay_help">تعداد درخواست‌های موازی هر بار. ۱ عادی است؛ روی لینک‌های با افت، ۲-۳ را امتحان کنید.</string>

android/app/src/main/res/values/strings.xml

@@ -67,6 +67,8 @@
     <!-- Advanced section -->
     <string name="adv_verify_tls">Verify upstream TLS</string>
     <string name="adv_verify_tls_help">Off disables cert checks for the Google edge. Only useful for debugging.</string>
+    <string name="adv_youtube_via_relay">Send YouTube through relay</string>
+    <string name="adv_youtube_via_relay_help">Route youtube.com / youtu.be / ytimg.com through Apps Script relay instead of SNI-rewrite tunnel. Avoids restricted mode but slower for video.</string>
     <string name="adv_log_level">log_level</string>
     <string name="adv_parallel_relay">parallel_relay: %1$d</string>
     <string name="adv_parallel_relay_help">Fan-out per request. 1 is normal; bump to 2-3 on lossy links.</string>