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  MultiSelectFilter (all superseded by the above)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/stores/background.svelte.ts

@@ -0,0 +1,118 @@
+import { PATTERNS, type BackgroundPatternId } from '$lib/desktop-patterns'
+
+export interface BackgroundConfig {
+  pattern: BackgroundPatternId
+  color: string // pattern foreground color, hex
+  fillColor: string | null // fill behind the pattern (its "gaps"); null = transparent, i.e. the app's own theme background shows through
+  opacity: number // 0..1
+  fade: number // 0..1 — 0 disables the vignette mask entirely
+  scale: number // pattern tile-size multiplier; 1 = natural size
+  rotation: number // degrees, 0..359
+}
+
+const STORAGE_KEY = 'oikos-desktop-bg'
+const VALID_IDS = new Set(PATTERNS.map((p) => p.id))
+
+// Matches the previous hardcoded desktop background (bubbles, brand blue,
+// tuned low so it reads as texture rather than noise) so this feature ships
+// as "now configurable" rather than a visual regression on first load.
+const DEFAULTS: BackgroundConfig = {
+  pattern: 'bubbles',
+  color: '#444cf7',
+  fillColor: null,
+  opacity: 0.08,
+  fade: 0,
+  scale: 1,
+  rotation: 0
+}
+
+function clamp01(v: unknown, fallback: number): number {
+  const n = typeof v === 'number' ? v : Number(v)
+  if (!Number.isFinite(n)) return fallback
+  return Math.min(1, Math.max(0, n))
+}
+
+function clampScale(v: unknown): number {
+  const n = typeof v === 'number' ? v : Number(v)
+  if (!Number.isFinite(n)) return DEFAULTS.scale
+  return Math.min(3, Math.max(0.4, n))
+}
+
+function clampRotation(v: unknown): number {
+  const n = typeof v === 'number' ? v : Number(v)
+  if (!Number.isFinite(n)) return DEFAULTS.rotation
+  return ((n % 360) + 360) % 360
+}
+
+function isHexColor(c: unknown): c is string {
+  return typeof c === 'string' && /^#[0-9a-fA-F]{6}$/.test(c)
+}
+
+function storedConfig(): BackgroundConfig {
+  if (typeof localStorage === 'undefined') return DEFAULTS
+  const raw = localStorage.getItem(STORAGE_KEY)
+  if (!raw) return DEFAULTS
+  try {
+    const parsed = JSON.parse(raw)
+    return {
+      pattern: VALID_IDS.has(parsed.pattern) ? parsed.pattern : DEFAULTS.pattern,
+      color: isHexColor(parsed.color) ? parsed.color : DEFAULTS.color,
+      fillColor: parsed.fillColor === null ? null : isHexColor(parsed.fillColor) ? parsed.fillColor : DEFAULTS.fillColor,
+      opacity: clamp01(parsed.opacity, DEFAULTS.opacity),
+      fade: clamp01(parsed.fade, DEFAULTS.fade),
+      scale: clampScale(parsed.scale),
+      rotation: clampRotation(parsed.rotation)
+    }
+  } catch {
+    return DEFAULTS
+  }
+}
+
+let config: BackgroundConfig = $state(storedConfig())
+
+function persist(): void {
+  if (typeof localStorage !== 'undefined') localStorage.setItem(STORAGE_KEY, JSON.stringify(config))
+}
+
+export function getBackground(): BackgroundConfig {
+  return config
+}
+
+export function setBackgroundPattern(pattern: BackgroundPatternId): void {
+  config = { ...config, pattern }
+  persist()
+}
+
+export function setPatternColor(color: string): void {
+  if (!isHexColor(color)) return
+  config = { ...config, color }
+  persist()
+}
+
+// null clears back to "auto" (transparent — the app's theme background
+// shows through the pattern's gaps).
+export function setFillColor(color: string | null): void {
+  if (color !== null && !isHexColor(color)) return
+  config = { ...config, fillColor: color }
+  persist()
+}
+
+export function setBackgroundOpacity(opacity: number): void {
+  config = { ...config, opacity: clamp01(opacity, DEFAULTS.opacity) }
+  persist()
+}
+
+export function setBackgroundFade(fade: number): void {
+  config = { ...config, fade: clamp01(fade, DEFAULTS.fade) }
+  persist()
+}
+
+export function setBackgroundScale(scale: number): void {
+  config = { ...config, scale: clampScale(scale) }
+  persist()
+}
+
+export function setBackgroundRotation(rotation: number): void {
+  config = { ...config, rotation: clampRotation(rotation) }
+  persist()
+}