feat(web): browse Knowledge Base by mixed Network/Fleet/Services/Storage/Identity/Knowledge categories

Replace the layer-based (Infrastructure/Governance/Cognition) browsing tabs
with a synthesized category taxonomy built from the ontology's finer-grained
`domain` field, since layer lumped unrelated entity types (an LXC and a DNS
record and a storage volume) into one bucket. Network and Fleet each span
two domains, so the table view now fans out per-domain fetches and merges,
while the graph view maps domain->category client-side. Also carries over
several detail-panel polish items (Tasks-not-raw-executions, slug URL
encoding, MultiSelectFilter) from earlier in this session.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/lib/components/DetailSection.svelte

@@ -18,16 +18,16 @@
   let open = $state(defaultOpen)
 </script>
 
-<Collapsible.Root bind:open class="rounded-lg border bg-card">
-  <Collapsible.Trigger class="flex w-full cursor-pointer select-none items-center justify-between gap-2 px-3 py-2 text-left hover:bg-muted/50">
-    <span class="text-sm font-medium">{title}{count !== undefined ? ` (${count})` : ''}</span>
+<Collapsible.Root bind:open class="rounded-md border bg-card">
+  <Collapsible.Trigger class="flex w-full cursor-pointer select-none items-center justify-between gap-2 px-2.5 py-1.5 text-left hover:bg-muted/50">
+    <span class="text-xs font-medium">{title}{count !== undefined ? ` (${count})` : ''}</span>
     <ChevronDownIcon
-      class="size-4 shrink-0 text-muted-foreground transition-transform duration-200 {open ? 'rotate-180' : ''}"
+      class="size-3.5 shrink-0 text-muted-foreground transition-transform duration-200 {open ? 'rotate-180' : ''}"
       aria-hidden="true"
     />
   </Collapsible.Trigger>
   <Collapsible.Content class="overflow-hidden data-[state=closed]:animate-out data-[state=closed]:fade-out data-[state=open]:animate-in data-[state=open]:fade-in">
-    <div class="border-t px-3 py-2.5">
+    <div class="border-t px-2.5 py-2">
       {@render children()}
     </div>
   </Collapsible.Content>