AuditLogViewer with filtering, sorting, and export

[gadyrcdz]

Overview

Implements the Audit Log Viewer UI described in the issue — a comprehensive interface for tracking portfolio events, changes, and actions with filtering, sorting, and export capabilities.

##closes #8

Changes

• AuditLogViewer — main container managing filter state (date range, event types, search) and rendering the table + modal
• AuditLogTable — table built with @tanstack/react-table, includes client-side sorting and pagination (10 items/page); switches to a card-based layout on mobile (<md)
• DateRangeFilter — native date inputs for from/to filtering
• EventTypeFilter — multi-select dropdown with checkboxes, closes on outside click
• EventDetailModal — shows full event details on row/card click; closes on Escape, backdrop click, or the close button
• StateComparison — before/after diff view, used inside the modal for events with state changes (e.g. settings_changed)
• ExportButton — exports the currently filtered event set as JSON or CSV
• AuditEvent type added to src/types/, following the existing pattern (Asset, RiskScore, etc.) and re-exported from index.ts
• Mock dataset (examples/mockAuditEvents.ts) with 1200 events for development and to validate rendering performance
• New dependency: @tanstack/react-table (added to package.json)

Acceptance Criteria

• Audit log table displays events with all required columns (timestamp, event type, action, result)
• Date range filtering works correctly and updates results
• Event type multi-select filter functions as expected
• Search finds events by action, type, or result
• Sorting works on all columns
• Export produces valid JSON and CSV files with complete (filtered) data
• Event detail modal shows comprehensive event information
• State comparison clearly highlights changes (before/after)
• Performance: table renders 1000+ events smoothly (tested with 1200 mock events)
• Mobile view provides usable experience (dedicated card layout, stacked filters)

Notes for reviewers

• The component currently reads from mockAuditEvents — there's a TODO marking where this should be swapped for a real API call once the audit events endpoint exists (see AuditLogViewer.tsx).
• No dedicated tests were added, as the issue didn't specify test requirements. Happy to add coverage for AuditLogTable, AuditLogViewer, and the CSV export logic if desired — let me know.
• Sorting by column header is desktop-only (mobile uses cards to prioritize a simpler tap-friendly layout); pagination controls are shared between both views.

Screenshots

Mobile

Desktop