feat(doctor): per-source-kind capability breakdown line

Studio's Doctor page _ModulesPanel now shows the source
breakdown directly under the module/capability count:

  Modules: 6 loaded, 10 capabilities
  6 bundle · 3 mcp · 1 system

Reads `CapabilityEntry.sourceKind` (Phase D wire field).
Pre-0.12 hubs return empty sourceKind; the breakdown panel
falls back to grouping by the legacy `kind` string so older
deployments still see a useful count.

Two data-layer additions:
  - `DoctorSnapshot.capabilitiesBySource: Map<String, int>`
  - `_sourceBreakdown(Map<String, int>) -> String` renders
    the line in deterministic alphabetical order.

dart analyze + flutter test green (11 integration tests).

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

lib/pages/doctor.dart

@@ -656,6 +656,15 @@ class _DaemonActionsCardState extends State<_DaemonActionsCard> {
   }
 }
 
+/// Format the per-source-kind capability count map as a
+/// human-readable line like "6 bundle · 3 mcp · 1 system".
+/// Sorted alphabetically for deterministic rendering.
+String _sourceBreakdown(Map<String, int> bySource) {
+  final entries = bySource.entries.toList()
+    ..sort((a, b) => a.key.compareTo(b.key));
+  return entries.map((e) => '${e.value} ${e.key}').join(' · ');
+}
+
 class _ModulesPanel extends StatelessWidget {
   final DoctorSnapshot snapshot;
 
@@ -677,14 +686,29 @@ class _ModulesPanel extends StatelessWidget {
                 color: theme.colorScheme.onSurfaceVariant,
               ),
               const SizedBox(width: FaiSpace.sm),
-              Text(
-                l.doctorModulesPanelSummary(
-                  snapshot.moduleCount,
-                  snapshot.capabilityCount,
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      l.doctorModulesPanelSummary(
+                        snapshot.moduleCount,
+                        snapshot.capabilityCount,
+                      ),
+                      style: theme.textTheme.bodyMedium,
+                    ),
+                    if (snapshot.capabilitiesBySource.isNotEmpty) ...[
+                      const SizedBox(height: 2),
+                      Text(
+                        _sourceBreakdown(snapshot.capabilitiesBySource),
+                        style: theme.textTheme.bodySmall?.copyWith(
+                          color: theme.colorScheme.onSurfaceVariant,
+                        ),
+                      ),
+                    ],
+                  ],
                 ),
-                style: theme.textTheme.bodyMedium,
               ),
-              const Spacer(),
               FaiPill(
                 label: snapshot.moduleCount > 0
                     ? l.doctorPillLoaded