fix(web): scope 1-hop neighbor expansion to rooted graph views only

Two bugs found while verifying against real production data:

- Excluded activity types (execution/check/task etc., see categories.ts)
  were falling through inCategory's "unknown type -> always visible"
  fallback, since typeCategory only stored entries whose category was
  defined. That fallback exists for types the ontology never returned at
  all; it wrongly re-admitted types the ontology returned but categories.ts
  deliberately excludes. Fixed by storing every type (including undefined
  categories) and checking key presence, not value truthiness.

- Once that was fixed, the previous commit's 1-hop neighbor expansion
  (dimmed cross-category context) turned out fine for a rooted view but
  flooded an unrooted "browse the whole category" view: Fleet's ~49 focus
  entities are hub-like enough that 1-hop pulled in 325+ of the system's
  479 total entities. Neighbor expansion now only applies when a root is
  set; the unscoped view goes back to same-category-only edges, which
  measured at a clean 49 nodes for Fleet.

Verified against live production data (real bearer token, real DB) rather
than mocks: Fleet unrooted = 49 nodes matching the DB's compute+physical
count exactly; rooting on host:strong shows 33 nodes with both bright
same-category and dimmed cross-category neighbors, no isolated dots.

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

web/src/lib/components/EntityGraph.svelte

@@ -66,8 +66,11 @@
   let sim: Simulation<Node, Link> | null = null
 
   // type → browsing category, so the graph can be scoped client-side (the
-  // graph endpoint itself has no category/domain param).
-  let typeCategory = $state<Map<string, Category>>(new Map())
+  // graph endpoint itself has no category/domain param). Value is undefined
+  // for types deliberately excluded from every category (e.g. execution/
+  // check/task — see categories.ts); the key is still present so inCategory
+  // can tell "excluded on purpose" apart from "not in the ontology at all."
+  let typeCategory = $state<Map<string, Category | undefined>>(new Map())
 
   let hoveredId = $state<string | null>(null)
 
@@ -108,11 +111,13 @@
     return typeof end === 'object' ? end.id : end
   }
 
-  // Node belongs to the active category? (Unknown types fall back to visible
-  // so a missing ontology entry never blanks the graph.)
+  // Node belongs to the active category? Types the ontology never returned
+  // at all fall back to visible (so a missing entry never blanks the
+  // graph); types the ontology returned but categories.ts deliberately
+  // excludes (key present, value undefined) do not.
   function inCategory(type: string): boolean {
-    const c = typeCategory.get(type)
-    return c === undefined || c === category
+    if (!typeCategory.has(type)) return true
+    return typeCategory.get(type) === category
   }
 
   async function load() {
@@ -162,9 +167,7 @@
 
   onMount(() => {
     fetchEntityTypes().then((types) => {
-      typeCategory = new Map(
-        types.map((t) => [t.name, typeToCategory(t.name, t.domain)]).filter((e): e is [string, Category] => e[1] !== undefined)
-      )
+      typeCategory = new Map(types.map((t) => [t.name, typeToCategory(t.name, t.domain)]))
       // Re-derive the active node types now that category membership is known.
       activeNodeTypes = new Set(nodes.filter((n) => inCategory(n.type)).map((n) => n.type))
     })
@@ -259,11 +262,17 @@
   // Real infra relationships mostly cross category lines (a service sits on
   // a network, uses storage, runs on an lxc — different categories under
   // this taxonomy). Hard-hiding any edge whose other end isn't in-category
-  // left focus nodes looking like disconnected dots. Instead, pull in their
-  // 1-hop neighbors (any category) so the edges — and what they connect
-  // to — stay visible, just visually secondary (see nodeOpacity).
+  // left focus nodes looking like disconnected dots. Rooted views (the user
+  // is exploring out from one entity) pull in 1-hop neighbors of any
+  // category, dimmed, so the edges — and what they connect to — stay
+  // visible. Unscoped "browse the whole category" views (no root) skip
+  // this: with ~50 focus nodes that touch nearly everything, 1-hop
+  // expansion floods in most of the graph (measured: 417 of 479 total
+  // entities for an unrooted Fleet view) — worse than the isolated-dot
+  // problem it was meant to fix. There, same-category-only edges stay.
   const neighborNodeIds = $derived.by(() => {
     const neighbors = new Set<string>()
+    if (!root.trim()) return neighbors
     for (const l of links) {
       if (!activeRelTypes.has(l.type)) continue
       const s = endpointId(l.source)