refactor: migration from sqlite to postgres with migration script (#483)

server/migration.load

@@ -0,0 +1,16 @@
+LOAD DATABASE
+     FROM sqlite:///app/reflector.sqlite3
+     INTO pgsql://reflector:reflector@postgres:5432/reflector
+WITH
+    include drop,
+    create tables,
+    create indexes,
+    reset sequences,
+    preserve index names,
+    prefetch rows = 10
+SET
+    work_mem to '512MB',
+    maintenance_work_mem to '1024MB'
+CAST
+    column transcript.duration to float using (lambda (val) (when val (format nil "~f" val)))
+;