[code] refactor, clippy, rustfmt

- added clippy lints and fixed the resulting issues
- moved build_possible_values_db() into the new() call
- extracted the skip_db functionality into their own functions

Cargo.toml

@@ -4,6 +4,11 @@ version = "0.1.0"
 authors = ["ddidderr <ddidderr@paul.network>"]
 edition = "2021"
 
+[lints.clippy]
+pedantic = { level = "warn", priority = -1 }
+todo = "warn"
+unwrap_used = "warn"
+
 [dependencies]
 
 [profile.release]