chore: commit pending ZXDB explorer changes prior to index perf work

Context
- Housekeeping commit to capture all current ZXDB Explorer work before index-page performance optimizations.

Includes
- Server-rendered entry detail page with ISR and parallelized DB queries.
- Node runtime for ZXDB API routes and params validation updates for Next 15.
- ZXDB repository extensions (facets, label queries, category queries).
- Cross-linking and Link-based prefetch across ZXDB UI.
- Cache headers on low-churn list APIs.

Notes
- Follow-up commit will focus specifically on speeding up index pages via SSR initial data and ISR.

Signed-off-by: Junie@lucy.xalior.com