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/main.dart

@@ -98,6 +98,9 @@ Future<void> main() async {
   // The kernel MessageBus, captured post-boot so `ui.open` can drive the GUI
   // readers (publish a 'selection') from the CLI — the drive-half of D-6 (T-231).
   MessageBus? kernelMessages;
+  // The filter-state cache, captured post-boot so `ui.filter` can read a
+  // box's current value back — the observe-half of D-6 (T-270).
+  FilterStateCache? kernelFilterStates;
   // IPC socket server (T-99 / T-124, per D-70/71/72). One server per
   // workspace; restarted when the active project switches because the
   // socket path is workspace-derived. The local DaemonClient connects
@@ -216,7 +219,11 @@ Future<void> main() async {
     // `clide ui open <reader> <id|path>` — drive the GUI readers from the CLI
     // (T-231, drive-half of D-6). Publishes a 'selection' to the kernel
     // MessageBus, captured post-boot; null in headless contexts.
-    registerUiCommands(dispatcher, () => kernelMessages?.publish);
+    registerUiCommands(
+      dispatcher,
+      () => kernelMessages?.publish,
+      filterValue: (address) => kernelFilterStates?.get(address),
+    );
     // `clide image show <path>` — drive an image card into the Claude
     // conversation log (T-249, drive-half of D-6). Resolves the path
     // (workspace-relative → absolute, must exist) here where workRoot is in
@@ -340,6 +347,7 @@ Future<void> main() async {
   // only reads it at request time (post-boot), so capturing it here is safe.
   kernelReaderNav = services.readerNav;
   kernelMessages = services.messages;
+  kernelFilterStates = services.filterStates;
   // Tee the IPC/MCP logger into the shared ring so the output dock (T-54)
   // shows socket-side logs alongside kernel/extension ones.
   ipcLog.addSink(services.logRing.add);