Terminal utf8 and reconnect (#14895)

* fix: handle incomplete UTF-8 sequences in terminal output, rework on https://github.com/rustdesk/rustdesk/pull/14736

* Fix terminal auto-reconnect freeze:  reconnect resumes terminal output, while multi-tab reconnect avoids restoring duplicate tabs for terminals that are already open.

* fix(terminal): subtract with overflow

```
thread '<unnamed>' panicked at src\server\terminal_service.rs:476:17:
attempt to subtract with overflow
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'tokio-runtime-worker' panicked at src\server\terminal_service.rs:1576:50:
called `Result::unwrap()` on an `Err` value: PoisonError { .. }
[2026-04-25T07:17:34Z ERROR librustdesk::server::service] Failed to join thread for service ts_9badd3fe-2411-4996-9f40-93c979009edd, Any { .. }
```

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix ios enter: https://github.com/rustdesk/rustdesk/issues/14907

* fix(terminal): reconnect, error handling

1. Terminal shows "^[[1;1R^[[2;2R^[[>0;0;0c"
2. NaN

```
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Converting object to an encodable object failed: NaN
...
```

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): dialog, close window

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): close terminal window on disconnect dialog

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): merge reconnect backlog into replay output

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): avoid reconnect stalls and delayed layout writes

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): remove invalid test

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): schedule frame before flushing buffered output

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): windows&macos, charset utf-8

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): reconnect suppress next output

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix: cap terminal reconnect replay output

  - split reconnect replay backlog into capped chunks
  - mark terminal data replay chunks for client-side suppression
  - avoid using open-message text to suppress xterm replies
  - reuse default terminal padding value
  - remove misleading Enter-key normalization PR link

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): env en_US.UTF-8

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): reconnect, refactor

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): flag, retry output

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): update hbb_common

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): comments

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): comments utf-8 chunk accumulator

Signed-off-by: fufesou <linlong1266@gmail.com>

* fix(terminal): update hbb_common

Signed-off-by: fufesou <linlong1266@gmail.com>

---------

Signed-off-by: fufesou <linlong1266@gmail.com>
Co-authored-by: fufesou <linlong1266@gmail.com>

flutter/lib/desktop/pages/terminal_page.dart

@@ -27,6 +27,7 @@ class TerminalPage extends StatefulWidget {
   final bool? isSharedPassword;
   final String? connToken;
   final int terminalId;
+
   /// Tab key for focus management, passed from parent to avoid duplicate construction
   final String tabKey;
   final SimpleWrapper<State<TerminalPage>?> _lastState = SimpleWrapper(null);
@@ -43,6 +44,9 @@ class TerminalPage extends StatefulWidget {
 
 class _TerminalPageState extends State<TerminalPage>
     with AutomaticKeepAliveClientMixin {
+  static const EdgeInsets _defaultTerminalPadding =
+      EdgeInsets.symmetric(horizontal: 5.0, vertical: 2.0);
+
   late FFI _ffi;
   late TerminalModel _terminalModel;
   double? _cellHeight;
@@ -155,13 +159,27 @@ class _TerminalPageState extends State<TerminalPage>
   // extra space left after dividing the available height by the height of a single
   // terminal row (`_cellHeight`) and distributing it evenly as top and bottom padding.
   EdgeInsets _calculatePadding(double heightPx) {
-    if (_cellHeight == null) {
-      return const EdgeInsets.symmetric(horizontal: 5.0, vertical: 2.0);
+    final cellHeight = _cellHeight;
+    if (!heightPx.isFinite ||
+        heightPx <= 0 ||
+        cellHeight == null ||
+        !cellHeight.isFinite ||
+        cellHeight <= 0) {
+      return _defaultTerminalPadding;
+    }
+    final rows = (heightPx / cellHeight).floor();
+    if (rows <= 0) {
+      return _defaultTerminalPadding;
+    }
+    final extraSpace = heightPx - rows * cellHeight;
+    if (!extraSpace.isFinite || extraSpace < 0) {
+      return _defaultTerminalPadding;
     }
-    final rows = (heightPx / _cellHeight!).floor();
-    final extraSpace = heightPx - rows * _cellHeight!;
     final topBottom = extraSpace / 2.0;
-    return EdgeInsets.symmetric(horizontal: 5.0, vertical: topBottom);
+    return EdgeInsets.symmetric(
+      horizontal: _defaultTerminalPadding.horizontal / 2,
+      vertical: topBottom,
+    );
   }
 
   @override