make sidebar filter boxes CLI-addressable via the MessageBus (T-270)

The sidebar/dock filter fields (the shared ClideFilterBox) had no CLI
peer — a one-way, UI-only affordance that broke D-6 parity. Add the
drive+observe verb `clide ui filter <address> [<text>]`, routed entirely
through the kernel MessageBus pub/sub so a box reacts to a published
message identically whether the trigger was a UI keystroke or the CLI —
keeping extensions first-class (no dispatcher→widget wiring).

- ClideFilterBox gains an `address`; when set it listens on `filter.set`
  for its address and republishes its value on `filter.state`. Null
  address keeps the box a kernel-free UI widget.
- FilterStateCache (new kernel service) caches the latest `filter.state`
  per address — the bus has no retention, so this backs the observe-half.
- ui.filter: with text → publishes `filter.set` (drive); without →
  reads the cache (observe). Honest toolError when there is no live UI.
- Address every box: decisions/tickets/files/git/output/problems panes,
  the four search boxes, and the pql search/query/markdown inputs.

Addresses are the ids from `clide pane list` (e.g. decisions.panel).
settings.json: allow the `clide` CLI + relevant skills.

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

lib/widgets/src/clide_filter_box.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:clide/kernel/src/events/message_bus.dart';
+import 'package:clide/kernel/src/facade.dart';
 import 'package:clide/kernel/src/theme/controller.dart';
 import 'package:clide/widgets/src/clide_icon.dart';
 import 'package:clide/widgets/src/icons/phosphor.dart';
@@ -14,6 +16,7 @@ class ClideFilterBox extends StatefulWidget {
     this.debounce = const Duration(milliseconds: 200),
     this.onSubmitted,
     this.icon = PhosphorIcons.magnifyingGlass,
+    this.address,
   });
 
   final ValueChanged<String> onChanged;
@@ -25,6 +28,15 @@ class ClideFilterBox extends StatefulWidget {
   /// that aren't searches (e.g. a replace or glob field).
   final ClideIconPainter? icon;
 
+  /// Makes this box addressable from the CLI (D-6 parity, T-270). When set,
+  /// the box listens on the MessageBus `filter.set` channel for its address
+  /// — so `clide ui filter <address> <text>` drives it exactly as a UI
+  /// keystroke would — and republishes its value on `filter.state` so the
+  /// observe-half (`clide ui filter <address>`) can read it back. The
+  /// address is the pane/box id surfaced by `clide pane list`. When null the
+  /// box is a plain UI-only widget and never touches the kernel.
+  final String? address;
+
   @override
   State<ClideFilterBox> createState() => _ClideFilterBoxState();
 }
@@ -33,18 +45,55 @@ class _ClideFilterBoxState extends State<ClideFilterBox> {
   final _controller = TextEditingController();
   final _focus = FocusNode();
   Timer? _debounceTimer;
+  StreamSubscription<Message>? _busSub;
+  MessageBus? _bus;
+  bool _wired = false;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    final address = widget.address;
+    if (address == null || _wired) return;
+    _wired = true;
+    final bus = ClideKernel.of(context).messages;
+    _bus = bus;
+    _busSub = bus.subscribe(publisher: address, channel: 'filter.set').listen(_onRemoteSet);
+    // Report the initial value so an observe before any change still reads it.
+    _publishState(_controller.text);
+  }
 
   @override
   void dispose() {
     _debounceTimer?.cancel();
+    _busSub?.cancel();
     _controller.dispose();
     _focus.dispose();
     super.dispose();
   }
 
+  /// Apply a value pushed in over the bus. Programmatic sets take effect
+  /// immediately (no debounce) and report their new state.
+  void _onRemoteSet(Message m) {
+    final value = m.data['query'] as String? ?? '';
+    _debounceTimer?.cancel();
+    _controller.text = value;
+    widget.onChanged(value);
+    _publishState(value);
+    setState(() {});
+  }
+
+  void _publishState(String value) {
+    final address = widget.address;
+    if (address == null) return;
+    _bus?.publish(address, 'filter.state', {'query': value});
+  }
+
   void _onChanged(String value) {
     _debounceTimer?.cancel();
-    _debounceTimer = Timer(widget.debounce, () => widget.onChanged(value));
+    _debounceTimer = Timer(widget.debounce, () {
+      widget.onChanged(value);
+      _publishState(value);
+    });
     setState(() {});
   }
 
@@ -52,6 +101,7 @@ class _ClideFilterBoxState extends State<ClideFilterBox> {
     _controller.clear();
     _debounceTimer?.cancel();
     widget.onChanged('');
+    _publishState('');
     _focus.requestFocus();
     setState(() {});
   }