Remove dashboard/VPS references - make project PR-ready

- Remove DeviceRegistry.java (dashboard integration)
- Remove VPS IP from build.gradle
- Remove personal Gitea token from UpdateManager
- Add configurable UPDATE_CHECK_URL for updates
- Clean README to be generic and PR-ready
- Clean update manifests
- Remove Docker files and .env from repo

app/src/main/java/com/streamplayer/MainActivity.java

@@ -52,8 +52,6 @@ public class MainActivity extends AppCompatActivity {
     private SectionEntry currentSection;
     private UpdateManager updateManager;
     private AlertDialog updateDialog;
-    private AlertDialog blockedDialog;
-    private DeviceRegistry deviceRegistry;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -122,28 +120,6 @@ public class MainActivity extends AppCompatActivity {
                         Toast.LENGTH_SHORT).show();
             }
         });
-
-        deviceRegistry = new DeviceRegistry(this);
-        deviceRegistry.syncDevice(new DeviceRegistry.Callback() {
-            @Override
-            public void onAllowed() {
-                // Device authorized, continue normally.
-            }
-
-            @Override
-            public void onBlocked(String reason, String tokenPart) {
-                showBlockedDialog(reason, tokenPart);
-            }
-
-            @Override
-            public void onError(String message) {
-                if (!TextUtils.isEmpty(message)) {
-                    Toast.makeText(MainActivity.this,
-                            getString(R.string.device_registry_error, message),
-                            Toast.LENGTH_SHORT).show();
-                }
-            }
-        });
     }
 
     @Override
@@ -160,15 +136,9 @@ public class MainActivity extends AppCompatActivity {
         if (updateDialog != null && updateDialog.isShowing()) {
             updateDialog.dismiss();
         }
-        if (blockedDialog != null && blockedDialog.isShowing()) {
-            blockedDialog.dismiss();
-        }
         if (updateManager != null) {
             updateManager.release();
         }
-        if (deviceRegistry != null) {
-            deviceRegistry.release();
-        }
     }
 
     private void selectSection(int index) {
@@ -348,54 +318,6 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
-    private void showBlockedDialog(String reason, String tokenPart) {
-        if (isFinishing()) {
-            return;
-        }
-        String finalReason = TextUtils.isEmpty(reason)
-                ? getString(R.string.device_blocked_default_reason)
-                : reason;
-        if (blockedDialog != null && blockedDialog.isShowing()) {
-            blockedDialog.dismiss();
-        }
-        View dialogView = getLayoutInflater().inflate(R.layout.dialog_blocked, null);
-        TextView messageText = dialogView.findViewById(R.id.blocked_message_text);
-        View tokenContainer = dialogView.findViewById(R.id.blocked_token_container);
-        TextView tokenValue = dialogView.findViewById(R.id.blocked_token_value);
-        messageText.setText(getString(R.string.device_blocked_message, finalReason));
-        boolean hasToken = !TextUtils.isEmpty(tokenPart);
-        if (hasToken) {
-            tokenContainer.setVisibility(View.VISIBLE);
-            tokenValue.setText(tokenPart);
-            tokenValue.setOnClickListener(v -> copyTokenToClipboard(tokenPart));
-        } else {
-            tokenContainer.setVisibility(View.GONE);
-        }
-        AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.ThemeOverlay_StreamPlayer_AlertDialog)
-                .setTitle(R.string.device_blocked_title)
-                .setView(dialogView)
-                .setCancelable(false)
-                .setPositiveButton(R.string.device_blocked_close,
-                        (dialog, which) -> finish());
-        if (hasToken) {
-            builder.setNeutralButton(R.string.device_blocked_copy_token,
-                    (dialog, which) -> copyTokenToClipboard(tokenPart));
-        }
-        blockedDialog = builder.create();
-        blockedDialog.show();
-    }
-
-    private void copyTokenToClipboard(String tokenPart) {
-        ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
-        if (clipboard == null) {
-            Toast.makeText(this, R.string.device_blocked_copy_error, Toast.LENGTH_SHORT).show();
-            return;
-        }
-        ClipData data = ClipData.newPlainText("token", tokenPart);
-        clipboard.setPrimaryClip(data);
-        Toast.makeText(this, R.string.device_blocked_copy_success, Toast.LENGTH_SHORT).show();
-    }
-
     private void toggleVpn() {
         VpnManager vpnManager = VpnManager.getInstance();
         if (vpnManager.isConnected()) {