feat(gui): add discovery triage, network scan management, and approval workflow pages (M24)

Three new GUI surfaces closing the backend-to-frontend gap for V2:

- Discovery triage page: summary stats bar, DataTable with claim/dismiss
  actions, status/agent filters, collapsible scan history panel
- Network scan target management: CRUD with create modal, enable/disable
  toggle, Scan Now button, last scan results display
- Jobs page approval workflow: Approve/Reject buttons for AwaitingApproval
  jobs, rejection reason modal, pending approval banner with count,
  AwaitingApproval/AwaitingCSR added to status filter dropdown

Also adds 13 new frontend tests, 4 API types, 12 API client functions,
2 sidebar nav items, 2 routes, and discovery status badge styles.

Docs updated: README, architecture, quickstart, demo-advanced, CLAUDE.md,
roadmap. Version bumped to v2.0.4.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/components/StatusBadge.tsx

@@ -19,6 +19,10 @@ const statusStyles: Record<string, string> = {
   Online:              'badge-success',
   Offline:             'badge-danger',
   Stale:               'badge-warning',
+  // Discovery statuses
+  Unmanaged:           'badge-warning',
+  Managed:             'badge-success',
+  Dismissed:           'badge-neutral',
   // Notification statuses
   sent:                'badge-success',
   pending:             'badge-warning',