setAutoCommit(false) sets the flag before BEGIN succeeds #108

LibsqlConnection.setAutoCommit(false) assigns this.autoCommit = false and then calls beginTransaction(). If BEGIN throws, the connection stays at autoCommit == false with baton == null.

After the failure:

• getAutoCommit() returns false.
• commit() throws "No transaction is active".
• The next statement silently begins a transaction.

#64 set out to remove this kind of state drift after a failure.

Expected:

• Assign the flag after beginTransaction() succeeds, or restore the previous value in a catch block.
• Add a test with a failing BEGIN.