test(predictions): add comprehensive test suite for usePredictions hooks

- Add 54 test cases covering all prediction hooks functionality
- Test usePredictionsReport, usePrediction, useRisks, useScenarios
- Test usePredictionsSummary, useUpdateScenario, useRiskCounts, useAllPredictions
- Test various filter combinations for risks (impact, probability, category)
- Test mutation operations with pending/success/error states
- Test query caching by data path, metric, horizon, and filters
- Test edge cases: empty data, missing fields, all risk categories
- Update coverage report (88.51% → 88.76%)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: aledlie