Change object model and add crate Error type

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+anyhow = "1.0.102"
 chrono = "0.4.44"
 clap = { version = "4.6.1", features = ["derive", "env"] }
 csv = "1.4.0"
@@ -11,4 +12,5 @@ directories = "6.0.0"
 reqwest = { version = "0.13.3", features = ["blocking"] }
 serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1.0.149"
+thiserror = "2.0.18"
 tokio = { version = "1.52.1", features = ["macros", "rt-multi-thread"] }