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/builtin/pql/src/pql_search_body.dart

@@ -103,11 +103,16 @@ class _PqlSearchBodyState extends State<PqlSearchBody> {
           children: [
             if (widget.mode == PqlPaneMode.markdown)
               ClideFilterBox(
+                address: 'search.pql.markdown',
                 hint: 'Filter markdown…',
                 onChanged: (v) => unawaited(c.loadMarkdownFiles(glob: v.isEmpty ? null : '**/*$v*.md')),
               )
             else
-              _PqlSearchInput(controller: c, dsl: widget.mode == PqlPaneMode.query),
+              _PqlSearchInput(
+                controller: c,
+                dsl: widget.mode == PqlPaneMode.query,
+                address: widget.mode == PqlPaneMode.query ? 'search.pql.query' : 'search.pql.vault',
+              ),
             if (c.error != null)
               Padding(
                 padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
@@ -146,13 +151,15 @@ class _PqlSearchBodyState extends State<PqlSearchBody> {
 }
 
 class _PqlSearchInput extends StatelessWidget {
-  const _PqlSearchInput({required this.controller, required this.dsl});
+  const _PqlSearchInput({required this.controller, required this.dsl, this.address});
   final PqlController controller;
   final bool dsl;
+  final String? address;
 
   @override
   Widget build(BuildContext context) {
     return ClideFilterBox(
+      address: address,
       hint: dsl ? 'PQL query…' : 'Search vault…',
       debounce: dsl ? Duration.zero : const Duration(milliseconds: 300),
       onChanged: dsl ? (_) {} : (v) => unawaited(controller.search(v)),