refactor: cleanup app.rs

[nozwock]

Refactor

• Remove explicitly stated data types where appropriate
• Replace complex code in favor of unwrap_or_default() for parsing of String to u64/f64
• Use mutable variable instead of its clone

[MrTanoshii]

Contributes to #3

[nozwock]

There's interval: u64 on L494 that can also be cleaned up of its data type

I was thinking of this rather

        let interval: u64 = (hr * 3600000) + (min * 60000) + (sec * 1000) + ms;

Let's leave that u64 out just for being lil explicit?

[MrTanoshii]

There's interval: u64 on L494 that can also be cleaned up of its data type

I was thinking of this rather

        let interval: u64 = (hr * 3600000) + (min * 60000) + (sec * 1000) + ms;

Let's leave that u64 out just for being lil explicit?

yeah that works too

[nozwock]

yeah that works too

Done

[MrTanoshii]

Thanks!