[codex] Refactor search pipeline orchestration

[ewlarson]

Summary

• Extract the Elasticsearch search request path into explicit orchestration layers: params, facet handling, geo filters, query building, execution, and response building.
• Preserve the existing search_resources public signature while moving the long in-function pipeline into smaller behavior-preserving collaborators.
• Fix two test-suite blockers found while validating locally: the WMS/WMTS migration seed swap and thumbnail alias redirects that pointed at missing cached images.

Why

This starts recommendation two from the pre-v1.0 review: split the search pipeline into understandable layers without changing response behavior. The goal is to make follow-up search work safer by isolating query construction, execution, facet aggregation, and response assembly.

Validation

• make lint
• make format
• COMPOSE_PROJECT_NAME=data-api WALLCLOCK_TIMEOUT_SECONDS=360 make test

Result: 1751 passed, 129 skipped, 1 xpassed; coverage 60.64%.