fix(sdk): propagate runtime-benchmarks and try-runtime to sp-runtime

Zepter requires that runtime-benchmarks and try-runtime features propagate
to all dependencies that support them, including sp-runtime.

Also adds unsigned-varint/std to std feature for completeness.

Fixes: zepter run check --config .config/zepter.yaml

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: mudigal

sdk/rust/Cargo.toml

@@ -59,6 +59,7 @@ std = [
 	"subxt",
 	"thiserror",
 	"tokio",
+	"unsigned-varint/std"
 ]
 
 # Enable for ink! smart contract compatibility
@@ -72,11 +73,13 @@ serde-support = ["serde"]
 # Runtime benchmarking (no-op for SDK, but required for workspace consistency)
 runtime-benchmarks = [
 	"pallet-transaction-storage/runtime-benchmarks",
+	"sp-runtime/runtime-benchmarks"
 ]
 
 # Try-runtime support (no-op for SDK, but required for workspace consistency)
 try-runtime = [
 	"pallet-transaction-storage/try-runtime",
+	"sp-runtime/try-runtime"
 ]
 
 # Note: Examples and integration tests are not included in the repository because they