feat(settings): parse reflector lists with CSV

Add CSV-based reflector list parsing with Serde reflector records.
The load_reflectors method reads a CSV file with reflector_ip,
ip_version, and description columns, validating IP version
consistency for each entry.

Cargo.toml

@@ -27,6 +27,7 @@ thiserror = "2.0"
 libc = "0.2"
 flume = { version = "0.12.0",  default-features = false, features = ["eventual-fairness", "select"] }
 config = { version = "0.15.25", default-features = false }
+csv = "1.4.0"
 serde = { version = "1", features = ["derive"] }
 
 [dependencies.log]