fix ClideStatusIndicator duplicate-key crash on rapid status flips (T-326)

AnimatedSwitcher cross-fades exiting + entering glyphs for 200ms; with a
fixed per-status ValueKey, flipping a status back (running -> success ->
running within the fade, e.g. two bound Claude panes) left two children
keyed 'running' in the Stack -> "Duplicate keys found" + a cascade of
follow-on framework errors. Make the indicator stateful and fold a
per-change sequence counter into the key, so each appearance is unique and
a same-status rebuild still doesn't re-animate. Regression test flips
status mid-cross-fade with real animations.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test/widgets/src/clide_status_indicator_test.dart

@@ -57,5 +57,37 @@ void main() {
       await tester.pumpAndSettle();
       expect(iconWith(CloseIcon), findsOneWidget);
     });
+
+    testWidgets('rapid status flips within the cross-fade do not collide (T-326)', (tester) async {
+      // Real animations (no disableAnimations) so the 200ms cross-fade overlaps
+      // exiting and entering glyphs — the condition that tripped a duplicate
+      // 'running' key. Pre-fix this threw "Duplicate keys found".
+      var status = ClideRunStatus.running;
+      late StateSetter set;
+      await tester.pumpWidget(harness(
+        f,
+        Center(
+          child: StatefulBuilder(builder: (ctx, s) {
+            set = s;
+            return ClideStatusIndicator(status: status);
+          }),
+        ),
+      ));
+
+      void flip(ClideRunStatus next) => set(() => status = next);
+
+      flip(ClideRunStatus.success);
+      await tester.pump(const Duration(milliseconds: 40));
+      flip(ClideRunStatus.running); // a 2nd 'running' while the 1st is still exiting
+      await tester.pump(const Duration(milliseconds: 40));
+      flip(ClideRunStatus.error);
+      await tester.pump(const Duration(milliseconds: 40));
+      flip(ClideRunStatus.success); // land on a static glyph
+      await tester.pump(const Duration(milliseconds: 40));
+
+      expect(tester.takeException(), isNull);
+      // Unmount so any in-flight spinner controller disposes (no pending timers).
+      await tester.pumpWidget(const SizedBox());
+    });
   });
 }