revive: cap remaining_gas to u64::MAX in substrate_execution

When calculating resource limits for nested calls through
substrate_execution::new_nested_meter, the ratio-based scaling
fails when deposit_left is very large (e.g., u128::MAX default).

The ratio becomes near-zero because:
- remaining_gas = weight_gas + deposit_gas (huge number from deposit)
- ratio = requested_gas / remaining_gas ≈ 0
- nested_weight_limit = ratio × weight_left ≈ 0

This causes proxy contracts using delegatecall to fail with OutOfGas
when called through ReviveApi.call, while the same calls succeed
through eth_transact.

Cap remaining_gas to u64::MAX since Ethereum gas is a u64 value.
This ensures the ratio is 1.0 when requesting all gas, giving the
nested call the full remaining weight.

Author: pgherveou

substrate/frame/revive/src/metering/math.rs

@@ -120,6 +120,12 @@ pub mod substrate_execution {
 						return Err(<Error<T>>::OutOfGas.into());
 					};
 
+					// Cap remaining_gas to u64::MAX since Ethereum gas is a u64 value.
+					// Without this cap, when deposit_left is very large (e.g., u128::MAX),
+					// the ratio calculation would produce a near-zero value, causing the
+					// nested call to receive almost no weight even when requesting all gas.
+					let remaining_gas = remaining_gas.min(u64::MAX.saturated_into());
+
 					let gas_limit = remaining_gas.min(*gas);
 
 					let ratio = if remaining_gas.is_zero() {