Add a send to Transmission action

migrations/2025-05-01-082736_create_transmission_processed/up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE transmission_processed
+(
+    id         INTEGER PRIMARY KEY,
+    magnet_id  INTEGER NOT NULL,
+    processed_at DATETIME NOT NULL,
+    FOREIGN KEY (magnet_id) REFERENCES magnets(id)
+);
+
+CREATE INDEX transmission_processed_magnet_id ON transmission_processed(magnet_id);