test(orm): add comprehensive QueryBuilder tests

[GaspardKirira]

Summary

Add automated tests for the complete QueryBuilder public surface.

The builder is lightweight but central to explicit custom ORM queries.

Current behavior

QueryBuilder supports:

• initial SQL construction;
• raw SQL fragments;
• spaces and newlines;
• typed parameters;
• NULL parameters;
• BLOB parameters;
• parameter binding;
• clearing;
• reserving;
• moving out SQL and parameters.

No automated tests protect these behaviors.

Expected behavior

Every public method must have deterministic unit-test coverage without requiring a database server.

Scope

• Test default construction.
• Test construction from initial SQL.
• Test raw().
• Test rawSpace().
• Test space().
• Test newline().
• Test every param() overload.
• Test paramNull().
• Test parameter order.
• Test bind() using a fake statement.
• Test reserve().
• Test clear().
• Test empty().
• Test takeSql().
• Test takeParams().
• Test the internal placeholder helper where appropriate.

Suggested files

• modules/orm/tests/query_builder_test.cpp
• modules/orm/tests/fakes/FakeStatement.hpp
• modules/orm/src/QueryBuilder.cpp
• modules/orm/include/vix/orm/QueryBuilder.hpp

Acceptance criteria

• SQL fragments preserve insertion order.
• Parameters preserve insertion order.
• Every parameter overload produces the expected DbValue.
• Binding starts at index one.
• clear() removes SQL and parameters.
• Move-out methods return the accumulated values.
• Tests require no live database.
• Existing public APIs remain unchanged.

Non-goals

This issue does not include:

• a full query DSL;
• SQL parsing;
• placeholder validation;
• repository filtering.

Suggested labels

• scope:orm
• type:ci
• tests
• good first issue
• status:ready