feat(ui): modern operator GUI with dashboard, reports list and system info API

[DeepZone]

Motivation

• Provide a modern, operator-friendly frontend layout with clear navigation and persistent result areas so checks are easier to read and act upon.
• Make the demo/read-only status visible to users and provide an accessible report history to review previous checks.
• Keep backend compatibility and avoid adding any write/deploy functionality while exposing a small read-only list endpoint to support the Reports view.

Description

• Reworked frontend to a multi-view operator layout with Header, left navigation, main content and footer system line, and views: Dashboard, ASN Check, Prefix Check, Reports, About (client-side navigation). (frontend/src/App.tsx, frontend/src/components/Layout.tsx)
• Improved ASN and Prefix check forms with clearer guidance, loading/error states and persistent results; ASN-Screen supports starting a separate ASN-RPKI batch and shows both results independently. (frontend/src/components/AsnCheckForm.tsx, frontend/src/components/PrefixCheckForm.tsx)
• Modularized and restyled report rendering with StatusBadge, recommendation list, raw-data sections, technical details, ASN-RPKI batch summary and sorted batch results; demo-mode banner is shown when report.details.demo_mode is true. (frontend/src/components/ReportView.tsx, frontend/src/components/StatusBadge.tsx, frontend/src/components/RawDataPanel.tsx)
• Added typed frontend API helpers and models for report listing and system info: getReports and getSystemInfo, and new types ReportListItem / SystemInfo. (frontend/src/api.ts, frontend/src/types.ts)
• Added backend read-only endpoints to support the UI: GET /api/reports (latest 50 reports, newest first) and GET /api/system/info (name/version/demo/read_only/data_sources), wired into the app router; existing report detail/markdown/html endpoints remain unchanged. (backend/app/api/routes_reports.py, backend/app/api/routes_system.py, backend/app/main.py)
• Added smoke tests for the new endpoints to the existing test suite. (backend/tests/test_api_smoke.py)

Testing

• Ran backend test suite with cd backend && pytest -q and all tests passed (37 passed, 24 warnings).
• Built the frontend with cd frontend && npm run build and the production build completed successfully (Vite build finished).

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Codex Task