fix(settings): reveal System-AI test result + refresh onboarding checklist

Two settings bugs the operator hit:

1. 'Test connection' appeared to do nothing. The result/error panel
   renders at the bottom of the System-AI editor's scrollable,
   600px-capped form, so on a tall dialog it lands below the fold —
   the footer button flickers 'Testing…' and nothing visible changes.
   The editor now holds a ScrollController and animates the content
   to reveal the outcome whenever a test result or error appears.

2. The welcome onboarding checklist kept 'connect System-AI'
   unchecked right after saving a working config. The checklist row
   opens the Settings dialog (an overlay, not a navigation), and on
   close the checklist never re-probed — so it showed the stale
   pre-config state. Both settings-opening rows (System-AI, MCP) now
   re-probe when the dialog closes; navigation-based rows already
   self-heal on return.

Studio suite green; flutter analyze clean.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/widgets/chain_system_ai_editor.dart

@@ -144,6 +144,7 @@ class _FaiSystemAiEditorState extends State<ChainSystemAiEditor> {
   String? _modelsError;
   AskAiResult? _testResult;
   String? _error;
+  final _scrollController = ScrollController();
   HardwareSnapshot? _hw;
   CuratedSnapshot? _curated;
   Map<String, CuratedModelInfo> _curatedById = const {};
@@ -200,9 +201,26 @@ class _FaiSystemAiEditorState extends State<ChainSystemAiEditor> {
     _endpoint.dispose();
     _model.dispose();
     _apiKeyEnv.dispose();
+    _scrollController.dispose();
     super.dispose();
   }
 
+  /// Reveal the test-result / error panel. It renders at the bottom
+  /// of a scrollable, height-capped form, so on a tall dialog it
+  /// lands below the fold — the operator taps "Test connection",
+  /// the footer button flickers, and nothing *visible* changes.
+  /// Scroll it into view so the outcome is never missed.
+  void _revealBottom() {
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!_scrollController.hasClients) return;
+      _scrollController.animateTo(
+        _scrollController.position.maxScrollExtent,
+        duration: const Duration(milliseconds: 250),
+        curve: Curves.easeOut,
+      );
+    });
+  }
+
   void _onProviderChanged(_ProviderPreset p) {
     setState(() {
       _preset = p;
@@ -255,6 +273,7 @@ class _FaiSystemAiEditorState extends State<ChainSystemAiEditor> {
         _saving = false;
         _error = e.toString();
       });
+      _revealBottom();
     }
   }
 
@@ -297,11 +316,13 @@ class _FaiSystemAiEditorState extends State<ChainSystemAiEditor> {
         _testing = false;
         _testResult = r;
       });
+      _revealBottom();
     } catch (e) {
       setState(() {
         _testing = false;
         _error = e.toString();
       });
+      _revealBottom();
     }
   }
 
@@ -375,6 +396,7 @@ class _FaiSystemAiEditorState extends State<ChainSystemAiEditor> {
       content: ConstrainedBox(
         constraints: const BoxConstraints(maxWidth: 520, maxHeight: 600),
         child: SingleChildScrollView(
+          controller: _scrollController,
           child: Column(
             mainAxisSize: MainAxisSize.min,
             crossAxisAlignment: CrossAxisAlignment.start,