register live GUI panes into clide pane list (T-219)

Per D-6 parity / D-83, make the kernel tabs the user sees (Claude,
Files, Editor, viewers) visible to the CLI. The PTY-backed PaneRegistry
can't model widget panes, so rather than mirror state (and risk drift),
pane.list snapshots the kernel PanelRegistry + LayoutArrangement at
request time via an injected view-pane source.

New Flutter-free ViewPane value type + snapshotViewPanes kernel bridge;
the daemonClientFactory now passes the PanelRegistry through so the
dispatcher can read it. pane.list merges PTY panes (source absent) with
UI tabs (source: ui, with slot/title/active/visible).

Acceptance (GUI-open: pane list enumerates live panes) needs a running
app to confirm end-to-end; unit-tested at the snapshot + dispatch level.

Closes T-219 (under T-218 / T-208 'Give Claude hands').

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

lib/kernel/src/facade.dart

@@ -115,7 +115,7 @@ class KernelServices {
     Locale? initialLocale,
     List<Locale> availableLocales = const [Locale('en', 'US')],
     String? socketPath,
-    DaemonClient Function(Logger, DaemonBus, LayoutArrangement)? daemonClientFactory,
+    DaemonClient Function(Logger, DaemonBus, LayoutArrangement, PanelRegistry)? daemonClientFactory,
     DaemonClient? isolateClient,
     bool autoStartDaemonClient = true,
     Toolchain? toolchain,
@@ -176,7 +176,7 @@ class KernelServices {
     );
     final ipc = isolateClient ??
         (daemonClientFactory != null
-            ? daemonClientFactory(log, events, arrangement)
+            ? daemonClientFactory(log, events, arrangement, panels)
             : DaemonClient(
                 // Legacy socket-client fallback — kept until T-127
                 // replaces it with the in-process socket loopback.