fix(db): add referee_type column to martial_judge_invite table

Add Flyway migration V7 to add referee_type field for storing referee type
(1-Chief Judge, 2-Judge, 3-General Judge) in invite records.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/main/resources/db/migration/V7__add_judge_invite_referee_type.sql

@@ -0,0 +1,3 @@
+-- Add referee_type column to martial_judge_invite table
+-- This field stores the referee type: 1-Chief Judge, 2-Judge, 3-General Judge
+ALTER TABLE martial_judge_invite ADD COLUMN referee_type INT DEFAULT NULL COMMENT '裁判类型：1-主裁判，2-裁判员，3-总裁';