perf: Implement cache warming for top queries

[KevinTCoughlin]

Summary

Pre-populate cache for popular search queries to reduce cold start latency.

Overview

Use a cron trigger to periodically fetch and cache results for the top N most popular queries.

Implementation Notes

• Add cron trigger to wrangler.toml:

  [triggers]
  crons = ["0 * * * *"]  # Every hour

• Use D1 trending data to identify top 50 queries
• Pre-fetch search results for each query
• Store in Cloudflare Cache API

Approach

1. Query D1 for top 50 queries from the last 7 days
2. For each query, make internal search request
3. Results get cached automatically via existing caching logic
4. Log cache warming metrics

Acceptance Criteria

• Cron job runs hourly
• Top 50 queries are pre-cached
• Cache warming doesn't exceed rate limits
• Metrics logged for monitoring
• Tests added for cache warming logic