feat(M01-B): 增加迁移执行器与旧库只读兼容层

scripts/dev/windows/check-backend.ps1

@@ -8,11 +8,16 @@ $requiredFiles = @(
   "backend/src/app.ts",
   "backend/src/config.ts",
   "backend/src/db/mysql.ts",
+  "backend/src/db/migration-runner.ts",
+  "backend/src/db/migrate-cli.ts",
+  "backend/src/db/legacy-read-repository.ts",
   "backend/src/routes/health.ts",
   "backend/src/server.ts",
   "backend/tests/backend-contract.test.mjs",
   "backend/tests/migration-contract.test.mjs",
   "backend/tests/mysql-pool-contract.test.mjs",
+  "backend/tests/migration-runner.test.mjs",
+  "backend/tests/legacy-read-repository.test.mjs",
   "database/migrations/2026061601_m01b_core_schema.up.sql",
   "database/migrations/2026061601_m01b_core_schema.down.sql",
   "database/migrations/2026061601_m01b_core_schema.verify.sql",
@@ -36,6 +41,11 @@ if ($LASTEXITCODE -ne 0) {
   throw "backend build failed"
 }
 
+& npm --prefix backend run db:migrate:plan
+if ($LASTEXITCODE -ne 0) {
+  throw "backend migration dry-run failed"
+}
+
 $oldHost = $env:QIPAI_API_HOST
 $oldPort = $env:QIPAI_API_PORT
 $oldVersion = $env:QIPAI_API_VERSION