Consolidate settings into 8 hubs and fix security vulnerabilities

Settings Consolidation (37+ pages to 8 hubs):
- Asset Type Hub: Unified type management with plugin descriptors
- Model Catalog Hub: Vendors, types, models, operating systems
- Asset Configuration Hub: Statuses, relationships, fields, identifiers
- Security Hub: Authentication, tokens, users, audit
- Site Configuration Hub: Site settings, floor map, branding, imports
- Integrations Hub: ServiceNow, Zabbix, Dell warranty
- Locations Hub: Locations, business units, employees
- Network Infrastructure Hub: VLANs, subnets

Plugin Descriptor Pattern:
- Add get_asset_type_descriptor hook to BasePlugin
- Implement descriptors in 6 plugins (printers, computers, machines, network, measuringtools, locations)
- Add /api/pluginui/asset-type-descriptors and core-type-descriptors endpoints
- Generic SubtypesTab component renders CRUD UI from descriptor schema

Security Fixes:
- Fix stored XSS via javascript: URIs in Models and Support Teams
- Add URL scheme validation (allow only http/https) in create/update endpoints
- Fix plugin contract violations in endpoints plugin (use shopdb.api imports)
- Add missing requiresAdmin guard to printer model supplies route
- Add user-facing error messages to API token load failures

Integration Improvements:
- Add persistent tab navigation to ServiceNow, Zabbix, and Dell Warranty settings
- Standardize integration settings UI across all three pages
- Fix tab visibility when navigating between integrations

Tested with 94-agent orchestrated review for ADR compliance and security.

frontend/src/views/settings/SecurityHub.vue

@@ -0,0 +1,118 @@
+<template>
+  <div class="security-hub">
+    <div class="hub-header">
+      <h2>Access & Security</h2>
+      <p class="description">Manage authentication, API tokens, users, roles, and audit logs</p>
+    </div>
+
+    <div class="tabs">
+      <router-link
+        :to="{ name: 'security-authentication' }"
+        class="tab"
+        :class="{ active: $route.name === 'security-authentication' }"
+      >
+        Authentication
+      </router-link>
+      <router-link
+        :to="{ name: 'security-tokens' }"
+        class="tab"
+        :class="{ active: $route.name === 'security-tokens' }"
+      >
+        API Tokens
+      </router-link>
+      <router-link
+        :to="{ name: 'security-users' }"
+        class="tab"
+        :class="{ active: $route.name === 'security-users' }"
+      >
+        Users & Roles
+      </router-link>
+      <router-link
+        :to="{ name: 'security-audit' }"
+        class="tab"
+        :class="{ active: $route.name === 'security-audit' }"
+      >
+        Audit Settings
+      </router-link>
+      <router-link
+        :to="{ name: 'security-auditlogs' }"
+        class="tab"
+        :class="{ active: $route.name === 'security-auditlogs' }"
+      >
+        Audit Logs
+      </router-link>
+    </div>
+
+    <div class="tab-content">
+      <router-view />
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { onMounted } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
+
+const route = useRoute()
+const router = useRouter()
+
+onMounted(() => {
+  if (route.name === 'security') {
+    router.replace({ name: 'security-authentication' })
+  }
+})
+</script>
+
+<style scoped>
+.security-hub {
+  max-width: 1400px;
+  margin: 0 auto;
+}
+
+.hub-header {
+  margin-bottom: 2rem;
+}
+
+.hub-header h2 {
+  margin: 0 0 0.5rem;
+  font-size: 1.75rem;
+}
+
+.description {
+  margin: 0;
+  color: var(--text-light);
+  font-size: 0.95rem;
+}
+
+.tabs {
+  display: flex;
+  gap: 0.25rem;
+  border-bottom: 1px solid var(--border-color);
+  background: var(--bg-secondary);
+  margin-bottom: 2rem;
+}
+
+.tab {
+  padding: 0.75rem 1.5rem;
+  text-decoration: none;
+  color: var(--text-light);
+  border-bottom: 2px solid transparent;
+  transition: all 0.15s;
+  font-weight: 500;
+  font-size: 0.95rem;
+}
+
+.tab:hover {
+  color: var(--text);
+  background: var(--hover-bg);
+}
+
+.tab.active {
+  color: var(--primary);
+  border-bottom-color: var(--primary);
+}
+
+.tab-content {
+  /* Content styled by child components */
+}
+</style>