(PATCH): Add integration tests for EF Core (SQL Server, PostgreSQL) and MongoDB

[PaulTrampert]

Adds PTrampert.QueryObjects.Integration.Test, an NUnit project that proves query objects translate and execute
against real databases rather than only against LINQ-to-Objects.

One suite, three databases

ProductQueryTests holds every expectation and is parameterized over an IProductStore. Three fixtures supply the
store, so the same 20 cases run against each:

Fixture	Category	Backing store
SqlServerProductQueryTests	SqlServer	EF Core + mcr.microsoft.com/mssql/server:2022-latest
PostgreSqlProductQueryTests	PostgreSql	EF Core + postgres:17-alpine
MongoDbProductQueryTests	MongoDb	MongoDB C# driver + mongo:8.2

Containers come from Testcontainers, one per fixture, started in [OneTimeSetUp]. Fixtures run in parallel so the
startups overlap.

Coverage

A single ProductQuery exercises every shipped attribute — EqualsQuery, NotEqualsQuery, the four comparison
attributes, StringContainsQuery, StringStartsWithQuery, AnyOfQuery, NoneOfQuery and ContainsQuery — over
string, Guid, bool, int, decimal, DateTime and List<string> properties. There are also cases for an
empty query object, a query with no matches, multiple criteria combined, and an IQueryObject<T> expression combined
with attribute filters.

Every provider under test throws rather than silently falling back to client-side evaluation, so a passing test is
also evidence the predicate reached the database. Notably, all three translate the Intersect(...).Any() form that
AnyOfQuery/NoneOfQuery build for a collection target.

Parameterization

EfCoreProductQueryTests adds three relational-only cases that verify the behaviour introduced in #68 end to end. A
DbCommandInterceptor captures the command as sent, and the tests assert that query values arrive as SQL parameters
rather than literals, that the same query shape produces byte-identical SQL for different values, and that
InlineValue = true embeds the literal and sends no parameters.

Notes

• The project is in the solution, so the existing pipeline's dotnet test <sln> picks it up. That means PR builds now
  need Docker and pull the SQL Server image; happy to split it into its own workflow instead if you'd rather keep the
  publish gate lighter.
• mongo:8.2 rather than 8.0: MongoDB 8.0 refuses to start on Linux kernels 6.19 and newer
  (SERVER-121912). Image tags are pinned in
  Stores/ContainerImages.cs.

Testing

dotnet test on the solution: 34 unit tests and 66 integration tests pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_018pK9kvAcxFsZ3KkYQcEZGP

[github-actions]

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