CodeBench: reqwest 0.13 + Docker volume cache + rust:latest

- reqwest 0.12 → 0.13, rustls-tls → rustls (golden, Dockerfile, promptit)
- Docker volume cache: kipina-cargo-registry + kipina-cargo-target
- rust:latest (1.94) + cmake (aws-lc-sys vaatii)
- Dockerfile yksinkertaistettu — esikäännös ei toimi, volume hoitaa
- Golden example 10/10 testattu uudella setupilla

kipina-codebench/golden-examples/todo-rs/Cargo.toml

@@ -12,5 +12,5 @@ sqlx = { version = "0.8", features = ["sqlite", "runtime-tokio"] }
 tower-http = { version = "0.6", features = ["cors"] }
 
 [dev-dependencies]
-reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }
+reqwest = { version = "0.13", default-features = false, features = ["json", "rustls"] }
 tokio = { version = "1", features = ["full", "test-util"] }