chore(workspace): Rust-воркспейс + скелет shturman-common

- workspace (resolver 2; members растут по планам)
- rust-toolchain 1.96.0; tracing-journald cfg-gated на Linux (кросс-платформенность)
- shturman-common: модули-скелеты paths/atomic/clock/log

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/shturman-common/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "shturman-common"
+version = "0.0.0"
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+tracing.workspace = true
+tracing-subscriber.workspace = true
+thiserror.workspace = true
+
+# journald — только Linux (на dev-Mac/в CI-non-Linux init_tracing падает в stderr)
+[target.'cfg(target_os = "linux")'.dependencies]
+tracing-journald.workspace = true
+
+[dev-dependencies]
+tempfile.workspace = true