feat(db): implement MySQL BLOB parameter binding

[GaspardKirira]

Summary

Implement Blob parameter binding in the MySQL driver.

SQLite already supports BLOB parameters, while the MySQL driver currently rejects them.

Current behavior

DbValue supports vix::db::Blob.

SQLiteStatement::bind() binds BLOB data through SQLite.

MySQLStatement::bind() throws DBError when the value contains a Blob.

Expected behavior

MySQL prepared statements must accept binary data through the existing Blob and blob() APIs.

Binary payloads must preserve embedded zero bytes and arbitrary byte values.

Scope

• Implement native MySQL binary parameter binding.
• Support empty BLOB values.
• Support data containing embedded zero bytes.
• Add MySQL integration tests.
• Verify resource ownership during binding.
• Preserve the existing public DB API.

Suggested files

• modules/db/src/mysql/MySQLDriver.cpp
• modules/db/tests/mysql_driver_test.cpp

Acceptance criteria

• Empty BLOB values can be inserted and retrieved.
• Binary data containing zero bytes round-trips correctly.
• Large test payloads within reasonable integration-test limits work.
• Binding failures are reported as DBError.
• SQLite BLOB behavior remains unchanged.
• Existing public APIs remain unchanged.

Non-goals

This issue does not include:

• streaming multi-gigabyte objects;
• file-to-BLOB convenience APIs;
• BLOB compression;
• ORM binary field mapping.

Suggested labels

• scope:db
• type:feature
• tests
• help wanted
• status:ready