feat: add constraint violation database exceptions

[memleakd]

Description

This builds on #9979 by extending the same typed-exception approach to other common database constraint violations.

Database constraint failures can now be represented by more specific exception types when the driver provides enough information:

• UniqueConstraintViolationException
• ForeignKeyConstraintViolationException
• NotNullConstraintViolationException
• CheckConstraintViolationException

All of them extend the new ConstraintViolationException, which still extends DatabaseException. UniqueConstraintViolationException keeps the same public purpose and remains catchable as a DatabaseException.

This lets applications handle common integrity errors directly with catch blocks instead of inspecting raw driver-specific error codes or matching error messages.

When a driver reports an integrity constraint violation that CodeIgniter cannot safely classify more precisely, the parent ConstraintViolationException is used instead. This keeps the behavior conservative.

The same typed exception is also available through getLastException() when DBDebug is disabled.

I kept the classification close to the existing UniqueConstraintViolationException implementation, but I am happy to adjust the hierarchy or naming if maintainers prefer a different shape.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

Overall, I like this direction. Could we add a few more live tests where the existing table structure allows it, particularly for NOT NULL updates and foreign-key violations?

[memleakd]

Thanks for the review @michalsn. I pushed updates for the cases you pointed out.

While checking the surrounding driver codes, I also added MySQL 3673 for the same NOT NULL bucket as 1048.

One small detail: I guarded MariaDB 4025 by message instead of treating the code alone as enough, because MariaDB documents it as ER_CONSTRAINT_FAILED, but MySQL uses the same numeric code for ER_INNODB_AUTOEXTEND_SIZE_OUT_OF_RANGE. I added a negative test for that MySQL case too.

References I checked:

• Oracle ORA-01407: https://docs.oracle.com/en/error-help/db/ora-01407
• MySQL 1216, 1217, 3673, 4025: https://dev.mysql.com/doc/mysql-errors/8.4/en/server-error-reference.html
• MariaDB 4025: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-4000-to-4099/e4025

[michalsn]

Thanks for the update.