feat(schedule)!: move schedule parser, downloader, and updater to external library

This can be used to support more schedule formats in the future.

src/state/env/schedule.rs

@@ -2,6 +2,7 @@ use std::env;
 
 #[derive(Clone)]
 pub struct ScheduleEnvData {
+    #[cfg(not(test))]
     pub url: Option<String>,
     pub auto_update: bool,
 }
@@ -9,6 +10,7 @@ pub struct ScheduleEnvData {
 impl Default for ScheduleEnvData {
     fn default() -> Self {
         Self {
+            #[cfg(not(test))]
             url: env::var("SCHEDULE_INIT_URL").ok(),
             auto_update: !env::var("SCHEDULE_DISABLE_AUTO_UPDATE")
                 .is_ok_and(|v| v.eq("1") || v.eq("true")),