Add Cmd+K command palette for searching executions and agents

Backend: add routeId, agentId, processorType filter fields to SearchRequest
and ClickHouseSearchEngine. Expand global text search to match route_id and
agent_id columns.

Frontend: new command palette component (portal overlay, Zustand store,
TanStack Query search hook with 300ms debounce, filter chip parsing,
keyboard navigation, scope tabs). Search bar in SearchFilters and TopNav
now open the palette. Selecting a result writes filters to the execution
search store to drive the results table.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cameleer3-server-core/src/main/java/com/cameleer3/server/core/search/SearchRequest.java

@@ -18,6 +18,9 @@ import java.time.Instant;
  * @param textInBody    full-text search scoped to exchange bodies
  * @param textInHeaders full-text search scoped to exchange headers
  * @param textInErrors  full-text search scoped to error messages and stack traces
+ * @param routeId       exact match on route_id
+ * @param agentId       exact match on agent_id
+ * @param processorType matches processor_types array via has()
  * @param offset        pagination offset (0-based)
  * @param limit         page size (default 50, max 500)
  */
@@ -32,6 +35,9 @@ public record SearchRequest(
         String textInBody,
         String textInHeaders,
         String textInErrors,
+        String routeId,
+        String agentId,
+        String processorType,
         int offset,
         int limit
 ) {