feat(web): replace 3D graph with fleet map, add desktop background patterns, rename Knowledge Base to Fleet

- FleetMap: service-centric host -> container -> service graph replacing
  the WebGL 3D force graph, with health coloring, hover-to-trace blast
  radius, and click-to-open
- Desktop background: configurable CSS pattern picker in Settings ->
  Appearance (8 patterns, color/fill/opacity/fade/size/rotation),
  replacing the hardcoded ambient graph background
- Fix missing data-orientation/data-disabled Tailwind custom variants so
  the shadcn Slider's track actually renders
- Rename "Knowledge Base" app to "Fleet"; scope its table to the same
  fleet entities as the graph (compute-entity descendants + service)
  instead of all entities
- Remove dead code: EntityGraph, GraphBackground, categories.ts,
  MultiSelectFilter (all superseded by the above)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/src/lib/components/desktop-shell/Desktop.svelte

@@ -9,7 +9,8 @@
   import { iconPositions, resetIconLayout } from '$lib/stores/icons'
   import { wm, openAppWindow, toggleShowDesktop } from '$lib/stores/windows'
   import { summary } from '$lib/stores/context'
-  import GraphBackground from '../GraphBackground.svelte'
+  import { getBackground } from '$lib/stores/background.svelte'
+  import { patternCss } from '$lib/desktop-patterns'
   import DesktopIcon from './DesktopIcon.svelte'
   import TaskLauncher from './TaskLauncher.svelte'
   import WindowLayer from './WindowLayer.svelte'
@@ -51,13 +52,42 @@
     if (e.shiftKey) wm.redo()
     else wm.undo()
   }
+
+  // Configurable in Settings → Appearance (see background.svelte.ts). Two
+  // layers, not one, because rotation and the fade mask need different
+  // geometry:
+  //  - outer: exactly the viewport box. Carries the fade mask, since a
+  //    vignette has to be centered on what's actually visible.
+  //  - inner: oversized (200%) and centered before rotating, so turning the
+  //    pattern doesn't pull its straight edges into view at the corners —
+  //    a viewport-sized box rotated in place would do exactly that.
+  const bgActive = $derived.by(() => {
+    const bg = getBackground()
+    return bg.pattern !== 'none' || bg.fillColor !== null
+  })
+  const bgOuterStyle = $derived.by(() => {
+    const bg = getBackground()
+    if (bg.fade <= 0) return ''
+    const stop = Math.round(100 - bg.fade * 70)
+    const mask = `radial-gradient(circle at 50% 50%, black 0%, black ${stop}%, transparent 100%)`
+    return `mask-image:${mask};-webkit-mask-image:${mask};`
+  })
+  const bgInnerStyle = $derived.by(() => {
+    const bg = getBackground()
+    const css = patternCss(bg.pattern, bg.color, bg.scale)
+    return `inset:-50%;width:200%;height:200%;opacity:${bg.opacity};background-color:${bg.fillColor ?? 'transparent'};transform:rotate(${bg.rotation}deg);${css}`
+  })
 </script>
 
 <svelte:window onkeydown={onWindowKeydown} />
 
 <div class="fixed inset-0 flex flex-col">
   <div class="relative min-h-0 flex-1 overflow-hidden" role="presentation">
-    <GraphBackground />
+    {#if bgActive}
+      <div class="pointer-events-none absolute inset-0 z-0 overflow-hidden" aria-hidden="true" style={bgOuterStyle}>
+        <div class="absolute" style={bgInnerStyle}></div>
+      </div>
+    {/if}
 
     <ContextMenu.Root {onOpenChange}>
       <!-- The bare-desktop hit area. Placed before the icons/windows layers

web/src/lib/components/desktop-shell/WindowLayer.svelte

@@ -32,6 +32,22 @@
       if (appId && !idx.has(appId)) wm.close(id)
     }
   })
+
+  // Keep an open app window's title in sync with its registry entry. The
+  // title is copied into the window at open time and then persisted, so a
+  // rename (e.g. "Knowledge Base" -> "Fleet") would otherwise stay stuck in
+  // the titlebar/taskbar of any already-open or hydrated window until it was
+  // closed and reopened. Mirrors the task-window title sync in windows.ts.
+  $effect(() => {
+    const idx = $appById
+    for (const id of $wmState.order) {
+      const appId = appIdFromWindowId(id)
+      const app = appId ? idx.get(appId) : undefined
+      if (app && $wmState.windows[id]?.title !== app.title) {
+        wm.update(id, { title: app.title })
+      }
+    }
+  })
 </script>
 
 <div use:dk.desktop class="absolute inset-0 z-40 pointer-events-none">