Expose tick interval constant and simplify handler

Move the 33 ms tick interval into `tick` as a public constant `TICK_MS`
and drop the parameter from `handle_tick_event`.
Update re‑exports and callers accordingly

src/app/threads/mod.rs

@@ -4,4 +4,4 @@ mod tick;
 
 pub use audio::{AudioCmd, SoundrackParts, Soundtrack, handle_audio};
 pub use events::handle_ct_events;
-pub use tick::handle_tick_event;
+pub use tick::{TICK_MS, handle_tick_event};