fix: add view history logic

backend/src/main/resources/db/migration/V9__add_post_reads.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS post_reads (
+  id BIGINT NOT NULL AUTO_INCREMENT,
+  user_id BIGINT NOT NULL,
+  post_id BIGINT NOT NULL,
+  last_read_at DATETIME(6) DEFAULT NULL,
+  PRIMARY KEY (id),
+  UNIQUE KEY UK_post_reads_user_post (user_id, post_id),
+  KEY IDX_post_reads_user (user_id),
+  KEY IDX_post_reads_post (post_id),
+  CONSTRAINT FK_post_reads_user FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE CASCADE,
+  CONSTRAINT FK_post_reads_post FOREIGN KEY (post_id) REFERENCES posts (id) ON DELETE CASCADE
+);