gRPC `ReadParams` also derives the wrong effective Plutus cost models (same symptom as #1274, different code path)

[adrian1-dot]

Related: #1274

Summary

Same underlying symptom as #1274 — Dolos returns the wrong effective PlutusV3 cost model for the current epoch — but via ReadParams in src/serve/grpc/v1alpha/query.rs, a separate code path from minibf's /epoch/*/parameters. Since it's separate code, it has its own separate wrong value, so it looks like both routes need the fix, not just one.

Examples

Measured on Preprod, 2026-09-11 (real protocol v11, 350 PlutusV3 params — cross-checked via Maestro and Koios epoch_params):

Source	protocol_major_ver returned	PlutusV3 param count
gRPC ReadParams	10	251 — matches the genesis-baked value exactly, looks like it never updates past genesis
minibf /epochs/latest/parameters	10	297 — a third value, see #1274
Real network	11	350

Suggested fix

Given both routes have the same symptom via different code, might be worth pulling the "pick the effective cost models for the current epoch" logic into one shared helper both crates/minibf and the gRPC server call, rather than fixing it twice and risking them drifting again later.

I'm working around this client-side for now with a hardcoded PlutusV3 override.