The /guardrails/usage/{overview,detail,logs} endpoints resolved guardrails only
from the litellm_guardrailstable Prisma table, so guardrails defined in
config.yaml (which live only in IN_MEMORY_GUARDRAIL_HANDLER) were invisible:
detail 404'd, overview omitted them or rendered them as Custom/Guardrail
orphans, and logs missed their logical-name alias.
Add config-owned accessors (list_config_guardrails, get_config_guardrail_by_id)
to the in-memory handler and use them in the usage endpoints, mirroring the
union/fallback already used by list_guardrails_v2 and get_guardrail_info. Also
preserve guardrail_info when storing a config guardrail (type/description were
dropped at initialize time) and read the Prisma-row / dict / LitellmParams
shapes uniformly.
Resolves LIT-2529
