refactor(frontend): split 7 oversized pages into feature co-location

Per guide ch.7 page split pattern (skeleton orchestrates, private
components live in features/<domain>/):
- InstancePage 1716->328, UsersPage 1309->240, TicketsPage 1076->195,
  TicketDetailPage 911->287, QueriesPage 883->479, LdapConfigPage 860->393,
  WorkflowPage 852->194
- new feature modules: datasource/ rbac/ ticket/ query/ system/ldap/
  governance/workflow/ (components + hooks + types + utils)
- stable keys replace index keys in dynamic lists; polling intervals
  and toast call sites preserved 1:1 (verified by agents)
- filter/pagination state moved to URL query via new useQueryState hook
  (Instance/Users/Tickets/AuditLogs pages): refresh/share/back-button
  restore state; composite updates applied atomically
- permission pure functions extracted to lib/permissions.ts (used by
  useAuth + useLogin); page-size audit: 0 pages over 700-line budget

frontend/vitest.config.ts

@@ -0,0 +1,14 @@
+import path from "path"
+import { defineConfig } from "vitest/config"
+
+export default defineConfig({
+  test: {
+    environment: "jsdom",
+    include: ["src/**/*.test.{ts,tsx}"],
+  },
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+})