Two-box throttle system + support top-up

- Server: two Xray inbounds (vless-normal / vless-throttled), 4GB threshold,
  management loop moves users between boxes instead of hard-killing.
  /session/status returns dynamic vless_path + is_throttled.
  Support ad callback (ad_type: support) extends session +30min +2GB.
  No hard quota kill — only 60-min expiry removes sessions.

- App: session_timer detects vless_path change in 5s poll, triggers
  silent reconnect (skipCleanup, skipAdBypass, quickReconnect).
  New support_button.dart for top-up rewarded ads.
  hivemind_service uses server vless_path instead of hardcoded constant.
  vpn_connection: skipAdBypass, quickReconnect, skipCleanup params.

- Config: Xray two-inbound template, nginx /tunnel-throttled with
  limit_rate 187k (1.5 Mbps). Updated AGENTS.md + SERVER_SETUP.md.

lib/components/support_button.dart

@@ -0,0 +1,84 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'package:revoltvpn/logic/ad_manager.dart';
+import 'package:revoltvpn/logic/session_timer.dart';
+import 'package:revoltvpn/logic/app_colors.dart';
+
+class SupportButton extends StatefulWidget {
+  const SupportButton({super.key});
+
+  @override
+  State<SupportButton> createState() => _SupportButtonState();
+}
+
+class _SupportButtonState extends State<SupportButton> {
+  bool _busy = false;
+
+  Future<void> _handleTap() async {
+    if (_busy) return;
+
+    final ad = context.read<AdManager>();
+    final timer = context.read<SessionTimer>();
+
+    // Only available when there's an active session.
+    if (!timer.isRunning && !timer.hasSyncedOnce) return;
+
+    setState(() => _busy = true);
+
+    try {
+      await ad.showAd('support');
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Consumer<SessionTimer>(
+      builder: (context, timer, _) {
+        if (!timer.isRunning && !timer.hasSyncedOnce) {
+          return const SizedBox.shrink();
+        }
+
+        return GestureDetector(
+          onTap: _handleTap,
+          child: Container(
+            padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 10),
+            decoration: BoxDecoration(
+              color: AppColors.glassBg,
+              borderRadius: BorderRadius.circular(24),
+              border: Border.all(
+                color: AppColors.accent.withAlpha(100),
+                width: 1,
+              ),
+            ),
+            child: Row(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                const Icon(Icons.favorite_border, color: AppColors.accent, size: 20),
+                const SizedBox(width: 8),
+                _busy
+                    ? const SizedBox(
+                        width: 18,
+                        height: 18,
+                        child: CircularProgressIndicator(
+                          strokeWidth: 2,
+                          color: AppColors.accent,
+                        ),
+                      )
+                    : const Text(
+                        'Support us \u2014 30 min!',
+                        style: TextStyle(
+                          color: AppColors.textWhite,
+                          fontSize: 14,
+                          fontWeight: FontWeight.w600,
+                        ),
+                      ),
+              ],
+            ),
+          ),
+        );
+      },
+    );
+  }
+}