Fix username change logging and saving. Re-enable migrations.

src/data/entities/NicknameHistoryEntry.ts

@@ -0,0 +1,16 @@
+import { Entity, Column, PrimaryColumn } from "typeorm";
+
+@Entity("nickname_history")
+export class NicknameHistoryEntry {
+  @Column()
+  @PrimaryColumn()
+  id: string;
+
+  @Column() guild_id: string;
+
+  @Column() user_id: string;
+
+  @Column() nickname: string;
+
+  @Column() timestamp: string;
+}