Add JUnit 5 tests for SQLDatabaseHandler

[tastybento]

Summary

• Adds SQLDatabaseHandlerTest, a new JUnit 5 test class for SQLDatabaseHandler
• 40 tests covering all public/protected methods and key branches

Coverage

Area	What's tested
Constructor / setDataSource	Schema creation on boot, rename path, null datasource disables plugin
createSchema	SQL exceptions on both schema and rename statements log errors
loadObjects	Empty result, valid JSON, multiple rows, null JSON, invalid JSON, SQLException
loadObject	Found/not-found, SQLException, useQuotes true/false
saveObject	Null, non-DataObject, plugin disabled (sync), plugin enabled (async queue), SQLException
deleteID	Queue population, runnable executes correct statement, useQuotes, SQLException
deleteObject	Null, non-DataObject, valid object queued
objectExists	True/false/no-row, SQLException, useQuotes
close	Sets shutdown flag
Async guard	Queue runnable abandoned when plugin disabled mid-flight

Test plan

• ./gradlew test --tests "world.bentobox.bentobox.database.sql.SQLDatabaseHandlerTest" — all 40 tests pass

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud