add decision detail view in context panel via MessageBus

Click a decision card in the sidebar → publishes on
builtin.decisions/selection → detail view loads full record →
context panel activates decisions.detail tab and renders:
- Type dot with tooltip, ID colored by type, domain badge
- Title, date
- Status badge for resolved questions

Same MessageBus pattern as ticket detail.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/builtin/decisions/src/decisions_view.dart

@@ -185,6 +185,7 @@ class _DecisionCard extends StatelessWidget {
     return Padding(
       padding: const EdgeInsets.only(bottom: 4),
       child: ClideTappable(
+        onTap: () => ClideKernel.of(context).messages.publish('builtin.decisions', 'selection', {'id': entry.id}),
         builder: (ctx, hovered, _) => Container(
           padding: const EdgeInsets.all(8),
           decoration: BoxDecoration(