feat(init): scaffold cargo workspace and CI

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

crates/core/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "log-viewer-core"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+thiserror.workspace = true
+notify.workspace = true
+toml.workspace = true
+parking_lot.workspace = true
+crossbeam-channel.workspace = true
+regex.workspace = true
+memchr.workspace = true
+directories.workspace = true
+
+[dev-dependencies]
+insta.workspace = true