feat(db): add grade_record_answers migration and update schema

- Add migration 0010 for grade_record_answers table

- Update shared DB schema with new table definitions

drizzle/0010_grade_record_answers.sql

@@ -0,0 +1,14 @@
+CREATE TABLE `grade_record_answers` (
+	`id` varchar(128) PRIMARY KEY NOT NULL,
+	`grade_record_id` varchar(128) NOT NULL,
+	`question_id` varchar(128) NOT NULL,
+	`score` decimal(6, 2) NOT NULL,
+	`full_score` decimal(6, 2) NOT NULL,
+	`feedback` text,
+	`created_at` timestamp DEFAULT (now()) NOT NULL,
+	`updated_at` timestamp DEFAULT (now()) NOT NULL,
+	CONSTRAINT `gra_gr_fk` FOREIGN KEY (`grade_record_id`) REFERENCES `grade_records`(`id`) ON DELETE cascade ON UPDATE no action,
+	CONSTRAINT `gra_q_fk` FOREIGN KEY (`question_id`) REFERENCES `questions`(`id`) ON DELETE cascade ON UPDATE no action
+);
+CREATE INDEX `grade_record_answers_record_idx` ON `grade_record_answers`(`grade_record_id`);
+CREATE INDEX `grade_record_answers_question_idx` ON `grade_record_answers`(`question_id`);