refactor: decide to not create separate table for subscriptions

migrations/2025-02-23-095541_initial/up.sql

@@ -29,41 +29,32 @@ create table devices (
     unique (user_id, device_id)
 );
 
-create table subscriptions (
-    id integer primary key not null,
-
-    url text unique not null
-);
-
 create table device_subscriptions (
     id integer primary key not null,
 
     device_id bigint not null
         references devices (id)
         on delete cascade,
-    subscription_id bigint not null
-        references subscriptions (id)
-        on delete cascade
+
+    podcast_url text not null,
 
     time_changed bigint not null default 0,
     deleted boolean not null default false,
 
-    unique (device_id, subscription_id)
+    unique (device_id, podcast_url)
 );
 
 create table episode_actions (
     id integer primary key not null,
 
-    subscription_id bigint not null
-        references subscriptions (id)
-        on delete set null,
-
     -- Can be null, as the device is not always provided
     device_id bigint
         references devices (id)
         on delete set null,
 
+    podcast_url text not null,
     episode_url text not null,
+
     timestamp bigint,
     action text not null,
     started integer,