Implement unified resource-query service and repository (DB allocation + Prometheus utilization)

Foundation layer for the new resource query API that replaces the legacy resource usage/stats endpoints. The legacy endpoints compute utilization from the now-dead kernel.last_stat column (with a Valkey fallback), so they are effectively non-functional. Build a clean service + repository that sources allocation from the DB and utilization from Prometheus.

Scope:
- Repository (repositories/resource_query/): query kernel resource allocation (occupied_slots-derived cpu/mem/gpu/shared_memory/disk + metadata: session, project, domain, agent, image, status, created/terminated) by domain/project/session/kernel over a time range. Port the existing kernel selection condition (terminated-in-period kernels in RESOURCE_USAGE_KERNEL_STATUSES OR running sessions created before end_date) from models/resource_usage.py / repositories/group db_source.
- Utilization from Prometheus: reuse the existing services/metric stack (MetricService/MetricRepository query_container_metric / query_container_live_stats) instead of kernel.last_stat or ValkeyStatClient.
- Service (services/resource_query/): aggregate kernels into a domain>project>session>kernel hierarchy with per-level totals (allocation + utilization). Define data/ types + Action/ActionResult + Processor.
- Define the unified domain data model here (data/resource_query/) consumed by the endpoint layer (separate issue).

Replaces the inconsistent legacy computations in models/resource_usage.py (parse_resource_usage\*), repositories/group/db_source and repositories/user/db_source.

## Success Criteria
- [ ] Repository returns per-kernel allocation for a given project + time range, grouped to session/project/domain
- [ ] Utilization values are sourced from the Prometheus metric service, NOT kernel.last_stat or ValkeyStatClient
- [ ] Kernel selection covers terminated-in-period kernels and still-running sessions (parity with legacy period condition)
- [ ] Service returns a domain>project>session>kernel hierarchy with correct per-level totals
- [ ] pants test passes for affected manager packages

JIRA Issue: BA-6447