test(scheduler): document that minutes are required in time format

"every day at 12" is misparsed by english-to-cron library.
Must use "at 12:00" format instead.

Author: aster-void

README.md

@@ -267,15 +267,17 @@ Full form:
 
 **Schedule**: Cron or English phrase
 
-- Cron: `min hour day month weekday` (e.g., `*/5 * * * *` = every 5 minutes)
+- Cron: `min hour day month weekday` (e.g., `*/5 * * * *`)
 - English examples:
   - `every 5 minutes`
   - `every day at 16:00`
   - `7pm every Thursday`
-  - `Sunday at 12:00`
-  - `midnight on Tuesdays`
-- 24-hour format preferred
-- 12-hour edge case: `12 am` = midnight (00:00), `12 pm` = noon (12:00)
+  - `noon` / `midnight`
+
+Notes:
+- Minutes required: `at 12:00` works, `at 12` does not
+- `every day` is optional: `noon` = `noon every day`
+- Avoid `12 am`/`12 pm`: use `noon`/`midnight` or `0:00`/`12:00`
 
 ### Environment variable priority
 

src/actor/job/tick.rs

@@ -186,6 +186,30 @@ mod tests {
         assert_eq!(next, Utc.with_ymd_and_hms(2025, 1, 15, 16, 0, 0).unwrap());
     }
 
+    #[test]
+    fn english_24h_requires_minutes() {
+        // "every day at 12" is NOT supported - library misparses it
+        let bad = english_to_cron::str_cron_syntax("every day at 12").unwrap();
+        assert_eq!(bad, "0 0 0 */1 * ? *"); // wrong!
+
+        // Must use "12:00" format
+        let good = english_to_cron::str_cron_syntax("every day at 12:00").unwrap();
+        assert_eq!(good, "0 0 12 */1 * ? *");
+    }
+
+    #[test]
+    fn english_noon_and_midnight() {
+        // "every day" is optional
+        assert_eq!(
+            english_to_cron::str_cron_syntax("noon").unwrap(),
+            english_to_cron::str_cron_syntax("noon every day").unwrap()
+        );
+        assert_eq!(
+            english_to_cron::str_cron_syntax("midnight").unwrap(),
+            english_to_cron::str_cron_syntax("midnight every day").unwrap()
+        );
+    }
+
     #[test]
     fn english_7pm_every_thursday() {
         let schedule = parse_schedule("7pm every Thursday");