enhance(server): add indexes for following host

packages/backend/migration/1644551208096-following-indexes.js

+const { MigrationInterface, QueryRunner } = require("typeorm");
+
+module.exports = class followingIndexes1644551208096 {
+    name = 'followingIndexes1644551208096'
+
+    async up(queryRunner) {
+        await queryRunner.query(`CREATE INDEX "IDX_4ccd2239268ebbd1b35e318754" ON "following" ("followerHost") `);
+        await queryRunner.query(`CREATE INDEX "IDX_fcdafee716dfe9c3b5fde90f30" ON "following" ("followeeHost") `);
+    }
+
+    async down(queryRunner) {
+        await queryRunner.query(`DROP INDEX "public"."IDX_fcdafee716dfe9c3b5fde90f30"`);
+        await queryRunner.query(`DROP INDEX "public"."IDX_4ccd2239268ebbd1b35e318754"`);
+    }
+}

packages/backend/src/models/entities/following.ts

@@ -41,6 +41,7 @@ export class Following {
 	public follower: User | null;
 
 	//#region Denormalized fields
+	@Index()
 	@Column('varchar', {
 		length: 128, nullable: true,
 		comment: '[Denormalized]',
@@ -59,6 +60,7 @@ export class Following {
 	})
 	public followerSharedInbox: string | null;
 
+	@Index()
 	@Column('varchar', {
 		length: 128, nullable: true,
 		comment: '[Denormalized]',