refactor: rename startWecker/stopWecker mutations to startRinging/stopRinging

'Wecker' is a Swiss-German term with no meaning in English.
Renaming to startRinging/stopRinging for better clarity.

api/schema.py

@@ -98,7 +98,7 @@ class Mutation:
         return False
 
     @strawberry.field
-    def start_wecker(self) -> bool:
+    def start_ringing(self) -> bool:
         """Start the wecker alarm if it is not already ringing.
         Returns True if started, False if already ringing."""
         if is_wecker_ringing():
@@ -110,7 +110,7 @@ class Mutation:
         return True
 
     @strawberry.field
-    def stop_wecker(self) -> bool:
+    def stop_ringing(self) -> bool:
         """Stop the wecker alarm if it is currently ringing.
         Returns True if stopped, False if not ringing."""
         if not is_wecker_ringing():