fix(session): don't release the session on a SOCKS5 Reconnect

Regression from e67f0b9, shipped in 3.3.7.

Reconnect repairs an orphaned proxy by tearing the runtime down and
re-attaching to the session the device already holds. It does that
through SessionTimer.disconnect(), which e67f0b9 taught to hand the
session back to the server - so it destroyed the very session the
following connect(resume: true) then asked for. Unawaited, so it raced:
the resume either found the session already gone or removed moments
later, surfacing as "Session not activated".

disconnect() now takes release, and the Reconnect path passes false.
Every other caller still hands the session back.

Narrow in practice: SOCKS5 mode only, only the Settings Reconnect
button, and the main-screen connect was unaffected because it mints a
new session anyway.

Co-Authored-By: Claude Opus 5 <[email protected]>

lib/logic/session_timer.dart

@@ -240,11 +240,17 @@ class SessionTimer extends ChangeNotifier with WidgetsBindingObserver {
     }
   }
 
-  Future<void> disconnect({String reason = 'User requested'}) async {
+  // release is false when the caller intends to re-attach to the same session,
+  // as the SOCKS5 Reconnect does: handing it back here would destroy the very
+  // session the follow-up connect(resume: true) is about to ask for.
+  Future<void> disconnect({
+    String reason = 'User requested',
+    bool release = true,
+  }) async {
     // Only here, not in _doDisconnect: this is the one path the user actually
     // asked for. Unawaited so a slow or unreachable API never holds up the
     // teardown.
-    unawaited(HivemindService.releaseSession());
+    if (release) unawaited(HivemindService.releaseSession());
     await _doDisconnect(reason);
   }