Please do the checklist before filing an issue:

• I have read the documentation, including the FAQ
• I can reproduce the bug using the latest prerelease version
• I have searched existing discussion and issue to avoid duplicates

Describe the bug

When a mapper class contains both a queryable projection method (IQueryable<A> -> IQueryable<B>) and a regular mapping method (A -> B) targeting a type with getter-only properties (expression-bodied or { get; } without a setter), Mapperly incorrectly emits RMG012 for those read-only properties on the regular mapping method.

Without the queryable projection method, no diagnostic is emitted (correct behavior). The presence of the projection triggers the false positive.

Repro
A link to a repro Gist or GitHub repository or a link to a Mapperly fork with a failing test.

Declaration code

public class A
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class B
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    // Computed property - no setter, cannot be mapped to
    public string FullName => $"{FirstName} {LastName}";
}

[Mapper]
public static partial class MyMapper
{
    // Having this projection method triggers the bug
    public static partial IQueryable<B> ProjectToB(this IQueryable<A> q);

    // RMG012: The member FullName on the mapping target type B
    // was not found on the mapping source type A
    public static partial B MapToB(this A source);
}

Removing the ProjectToB projection method eliminates the false RMG012 diagnostic on MapToB.

Actual relevant generated code

// The generated mapping code is correct (FullName is not assigned),
// but a spurious RMG012 warning is emitted for FullName.
public static partial B MapToB(this A source)
{
    var target = new B();
    target.FirstName = source.FirstName;
    target.LastName = source.LastName;
    return target;
}

Expected relevant generated code

// Same generated code, but without the RMG012 diagnostic for FullName.
public static partial B MapToB(this A source)
{
    var target = new B();
    target.FirstName = source.FirstName;
    target.LastName = source.LastName;
    return target;
}

Reported relevant diagnostics

• RMG012: The member FullName on the mapping target type B was not found on the mapping source type A

Environment (please complete the following information):

• Mapperly Version: 5.0.0-next.4 (also reproducible on current main)
• Nullable reference types: enabled
• .NET Version: .NET 10.0
• Target Framework: net10.0

Additional context
I will create a fix PR