feat(education): complete Flyway migration and atomic submit

sql/postgresql/education/007-education-favorite-rollback.sql

@@ -0,0 +1,25 @@
+-- =============================================
+-- Education 模块 — 收藏夹 DDL Rollback (PostgreSQL)
+-- Migration: 007
+-- =============================================
+-- IMPORTANT: This is a documentation-only rollback.
+--   No DROP/ALTER/DELETE statements are executed. The favorite
+--   table is provenance-safe: it only accumulates user preference
+--   data. Dropping this table would lose student favorites with
+--   no recovery path.
+--
+-- What this migration created:
+--   - education_favorite (new table)
+--   - idx_tenant_user (index)
+--   - idx_tenant_user_target_type (index)
+--   - uk_tenant_user_target (unique constraint)
+--
+-- Manual rollback requires:
+--   1. Verified database backup before rollback
+--   2. Operator approval (DBA sign-off)
+--   3. Provenance of all favorite records preserved (exported)
+--   4. Soft-delete via deleted = true before any hard drop
+--
+-- These tables are NOT deleted by this script. Favorite history is
+-- retained; if deletion is required by external policy, consult
+-- the DBA for a verified rollback procedure.