chore: establish development baseline

crates/bat-cas-engine/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "bat-cas-engine"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+
+[dependencies]
+anyhow.workspace = true
+thiserror.workspace = true
+blake3.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+tracing.workspace = true
+async-trait.workspace = true
+
+# 文件系统操作
+tokio = { workspace = true, features = ["fs", "io-util"] }
+
+# 数据库（用于引用计数、元数据管理）
+sqlx = { version = "0.8", features = ["runtime-tokio", "sqlite"] }
+
+# Hex 编码
+hex = "0.4"
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["test-util", "macros"] }
+tempfile = "3.14"