fix(coprocessor): add missing indexes on verify_proofs and dependence_chain tables

Author: antoniupop

coprocessor/fhevm-engine/db-migration/migrations/20260105120000_dependence_chain_proofs_indexing.sql

@@ -0,0 +1,11 @@
+-- Improve indexing for verify_proofs table
+
+CREATE INDEX IF NOT EXISTS idx_verify_proofs_verified_not_null
+ON verify_proofs (retry_count);
+
+-- Improve indexing for dependence_chain table
+
+CREATE INDEX IF NOT EXISTS idx_dependence_chain_unlock
+ON dependence_chain (lock_expires_at, last_updated_at)
+WHERE dependency_count = 0;
+