fix: intro/outro playlist unset was impossible (#3101)

this reinstates the boolean fields in the database from the original PR
to work around a foreign key contraint. THE UI remains unchanged
libretime/libretime@7992a9b

schema.yml

@@ -6412,9 +6412,13 @@ components:
         intro_playlist:
           type: integer
           nullable: true
+        override_intro_playlist:
+          type: boolean
         outro_playlist:
           type: integer
           nullable: true
+        override_outro_playlist:
+          type: boolean
     PatchedShowDays:
       type: object
       properties:
@@ -7250,9 +7254,13 @@ components:
         intro_playlist:
           type: integer
           nullable: true
+        override_intro_playlist:
+          type: boolean
         outro_playlist:
           type: integer
           nullable: true
+        override_outro_playlist:
+          type: boolean
       required:
         - auto_playlist_enabled
         - auto_playlist_repeat
@@ -7261,6 +7269,8 @@ components:
         - linked
         - live_enabled
         - name
+        - override_intro_playlist
+        - override_outro_playlist
     ShowDays:
       type: object
       properties: