feat: implement TTR preview functionality with caching and UI integration

backend/scripts/runMigrations.js

@@ -1,6 +1,23 @@
 import sequelize from '../database.js';
 
 const migrations = [
+  {
+    id: '20261005_create_match_ttr_preview_cache',
+    async up() {
+      await sequelize.query(`
+        CREATE TABLE IF NOT EXISTS match_ttr_preview_cache (
+          id INT AUTO_INCREMENT PRIMARY KEY,
+          match_id INT NOT NULL,
+          snapshot_date DATE NOT NULL,
+          payload JSON NOT NULL,
+          created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+          updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+          UNIQUE KEY uniq_match_ttr_preview_day (match_id, snapshot_date),
+          CONSTRAINT fk_match_ttr_preview_match FOREIGN KEY (match_id) REFERENCES \`match\`(id) ON DELETE CASCADE
+        )
+      `);
+    },
+  },
   {
     id: '20261005_add_hidden_test_user_flags',
     async up() {