Issue #223 AsNoTracking before Select Throws Argument Exception - #225

_AddProjectableSelect appends Select<TEntity, TEntity>, so it only composes
when the node really is a sequence of TEntity. It is not, whenever the caller
already projected away from the entity root, and appending the rewrite anyway
throws instead of no-oping:

  ArgumentException: Expression of type 'IQueryable<Dto>' cannot be used for
  parameter of type 'IQueryable<TEntity>' of method Select[TEntity,TEntity]

_disableRootRewrite is meant to prevent this -- a Select sets it -- but EFNext#132
gave that same field a second job, the tracking decision. ExpressionVisitor
walks outside-in, so in

  db.Set<T>().AsNoTracking().Where(...).Select(x => new Dto { ... }).ToList()

the AsNoTracking node is visited last and clears the flag the Select set,
re-enabling the rewrite against an IQueryable<Dto>. Any query that puts
AsNoTracking before a projection to a DTO or an anonymous type throws, which
is a common repository shape. Checking the node's own type is independent of
visit order, so it holds whichever of the two flags wrote last.

Deliberately an exact element-type match rather than an assignability check:
IQueryable<out T> is covariant, so IQueryable<TEntity> is assignable from
IQueryable<TDerived>, and rewriting there would re-project a derived entity as
its base type.

Tests: three new QueryRootTests cases covering AsNoTracking before a
projection to an anonymous type, the same via the context's default tracking
behaviour, and a projection that stays on the entity type (still rewritten).

Co-Authored-By: Claude Opus 5.5 <[email protected]>