fix(backend): ExportServiceTest SQLite - single connection for in-memory, busy_timeout on verify

- Database.initForTests: use pool size 1 and minimumIdle 0 for :memory: SQLite
  so export (on IO dispatcher) sees the same DB as test
- ExportServiceTest: add busy_timeout=5000 when opening exported file for verify;
  use requireNotNull for exported flag row

Made-with: Cursor

Author: MaxLuxs

backend/src/main/kotlin/flagent/repository/Database.kt

@@ -44,11 +44,13 @@ object Database {
      */
     fun initForTests(jdbcUrl: String, driverClassName: String = "org.postgresql.Driver") {
         close()
+        val isInMemorySqlite = jdbcUrl.contains(":memory:", ignoreCase = true)
         val config = HikariConfig().apply {
             this.driverClassName = driverClassName
             this.jdbcUrl = jdbcUrl
-            maximumPoolSize = 2
-            minimumIdle = 1
+            // SQLite :memory: is per-connection; pool size 1 so all code sees the same DB
+            maximumPoolSize = if (isInMemorySqlite) 1 else 2
+            minimumIdle = if (isInMemorySqlite) 0 else 1
             connectionTimeout = 30000
         }
         dataSource = HikariDataSource(config)

backend/src/test/kotlin/flagent/service/ExportServiceTest.kt

@@ -64,22 +64,19 @@ class ExportServiceTest {
         // Assert: Verify SQLite file is created and contains data
         assertTrue(sqliteBytes.isNotEmpty(), "SQLite export should return non-empty bytes")
 
-        // Verify by reading the SQLite file
+        // Verify by reading the SQLite file (busy_timeout for CI where SQLite can be briefly locked)
         val tempFile = File.createTempFile("test_export_", ".sqlite")
         try {
             tempFile.writeBytes(sqliteBytes)
-            
+            val url = "jdbc:sqlite:${tempFile.absolutePath}?busy_timeout=5000"
             val db = org.jetbrains.exposed.v1.jdbc.Database.connect(
-                url = "jdbc:sqlite:${tempFile.absolutePath}",
+                url = url,
                 driver = "org.sqlite.JDBC"
             )
-            
             transaction(db) {
                 val flagCount = Flags.selectAll().count()
                 assertEquals(1, flagCount, "Should export 1 flag")
-                
-                val exportedFlag = Flags.selectAll().where { Flags.id eq createdFlag.id }.firstOrNull()
-                assertNotNull(exportedFlag, "Exported flag should exist")
+                val exportedFlag = requireNotNull(Flags.selectAll().where { Flags.id eq createdFlag.id }.firstOrNull()) { "Exported flag should exist" }
                 assertEquals(createdFlag.key, exportedFlag[Flags.key], "Flag key should match")
                 assertEquals(createdFlag.description, exportedFlag[Flags.description], "Flag description should match")
             }