feat(education): complete Flyway migration and atomic submit

docs/education/migration/issues/EDU-006-practice-schema-flyway.md

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+# EDU-006 — Deliver Practice schema through module-owned Flyway
+
+- **Status:** done — V4030 delivered and verified on an isolated disposable PostgreSQL test database
+- **Type:** database implementation
+- **Phase:** 2 prerequisite
+- **Blockers:** EDU-005
+
+## Implementation result
+
+`V4030__create_and_adopt_practice_schema.sql` now owns the final Practice session/question, report/detail, wrong-question/idempotency, favorite, and unified idempotency schema. Fresh databases do not create legacy answer/submit idempotency tables. Compatible manually initialized Practice tables receive missing final columns and JSONB alignment; legacy answer/submit idempotency rows are backfilled into `education_idempotency` while the source tables remain untouched. A conflicting request hash fails the migration transactionally.
+
+The EDU-016 test seam now runs the real Flyway chain in a random disposable PostgreSQL schema. Its temporary `create_tables.sql` bridge was removed. The established 140 persistence tests and five migration-contract scenarios pass together.
+
+Manual Education SQL mounts were removed from Docker Compose, and the active Education README and Pilot runbook now describe PostgreSQL/Flyway forward-only delivery. V4010/V4020 remained byte-for-byte unchanged. V4040 was not created because the capability menu still lacks a complete admin UI/product decision; no empty placeholder version was introduced.
+
+No shared or production database was migrated. Successful migration evidence applies only to the isolated no-volume PostgreSQL container and random schemas used by the tests.
+
+## Scope
+
+Implement only the objects approved in EDU-005, potentially covering:
+
+- practice sessions and question snapshots;
+- answer and submit idempotency;
+- reports and report details;
+- wrong questions and favorites;
+- tenant-scoped unique constraints;
+- indexes required by verified query paths;
+- necessary menu/permission seed data;
+- compatible backfills for existing development data.
+
+Exact objects and versions are determined by EDU-005 and `flyway-postgresql`.
+
+## Architecture rules
+
+- Use PostgreSQL dialect only.
+- Tenant-scoped uniqueness includes `tenant_id` where required.
+- Database uniqueness is the final idempotency guard.
+- Use `ON CONFLICT` where approved by the design.
+- Do not copy Supabase auth/RLS as the application isolation model.
+- Do not add destructive rollback migrations.
+
+## Acceptance criteria
+
+- [x] New migrations use versions allocated by `flyway-postgresql`.
+- [x] V4010/V4020 remain unchanged as potentially distributed history.
+- [x] Migrations are packaged under `target/classes/db/migration/education/`.
+- [x] Annotated SQL and Mapper behavior match PostgreSQL constraints.
+- [x] Focused repository/integration tests cover uniqueness and tenant scope.
+- [x] Real PostgreSQL Flyway migrate/validate succeeds in an isolated disposable test environment.
+- [x] Operational docs no longer instruct users to apply MySQL or manual Education SQL for these objects.
+
+## Verification
+
+At minimum:
+
+```bash
+git diff --check
+mvn -pl yudao-module-education -am -DskipTests clean package
+find yudao-module-education/target/classes/db/migration/education -type f
+mvn -pl yudao-server -am -DskipTests clean compile
+```
+
+Also run the PostgreSQL commands prescribed by `flyway-postgresql` when an authorized database is available.
+
+## Verification performed
+
+Against an isolated PostgreSQL container bound only to `127.0.0.1`, the focused Flyway suite exercised fresh migration, baseline-4009 adoption, compatible session/question plus legacy-idempotency adoption, conflict with existing unified history, and conflicting duplicate legacy keys. Together with the existing persistence suite: 145 tests passed, 0 failures, 0 errors, 0 skipped. Every test schema was dropped and the no-volume container was stopped.
+
+Also completed:
+
+```text
+mvn -pl yudao-module-education -am -DskipTests clean package — BUILD SUCCESS
+V4010, V4020, V4030 present under target/classes/db/migration/education/
+mvn -pl yudao-server -am -DskipTests clean compile — BUILD SUCCESS
+git diff --check — passed
+```
+
+V4010 and V4020 retained their pre-ticket SHA-256 values. No shared or production PostgreSQL database was changed.
+
+## Risk and rollback
+
+- **Risk:** High data compatibility and deployment-order risk.
+- **Rollback:** Forward correction migration plus application rollback. Never use `clean` or destructive rollback in shared environments.