feat(analytics): Stream Analytics Explorer + filter/export engine

[bright5455]

closes #1472

• Multi-dimensional FilterToolbar (tokens, status incl. low_runway, role, date presets + custom range, runway threshold, debounced full-text search)
• KPI ribbon: TVS, outflow velocity, active positions, avg runway
• Stacked token-volume chart derived from filtered dataset
• Accounting export engine: CSV, JSON, QuickBooks/Xero CSV (15 columns)
• URL query param sync for shareable filter state
• Tests cover filter logic, zero state, CSV headers, and export bundles

Also fixes pre-existing TS strict errors that blocked tsc:

• guard possibly-undefined array/index accesses
• include format qualifier in export filename
• wrap tanstack refetch in void callback
• drop unused imports, ScVal cast, vitest imports in StellarExplorerLink test
• align ScheduleStep props at its call site

Description

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test addition or update

Related Issues

Closes #

Changes Made

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

Breaking Changes

Breaking Changes:

Migration Guide:

Screenshots/Demo

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Updated Postman/Hoppscotch API collections if routes changed
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked for breaking changes and documented them if applicable
• If this change adds or modifies a metric, I have updated the Grafana dashboard and the alert rules in backend/docs/observability/

Additional Notes