refactor: consolidate types, remove dead code, and fix minor bugs

Replace DayOfWeek with chrono::Weekday via extension traits, unify
RateLimitConfig into the config module, and remove the unused time
command, BannerState, and ClassDetails stub. Fix open_only query
parameter to respect false values and correct 12-hour time display.

Cargo.toml

@@ -55,6 +55,7 @@ mime_guess = { version = "2.0", optional = true }
 clap = { version = "4.5", features = ["derive"] }
 rapidhash = "4.1.0"
 yansi = "1.0.1"
+extension-traits = "2"
 
 [dev-dependencies]