Type variable defaults aren't checked properly against `TypeAliasType(...)` aliases

**Bug Report, To Reproduce, & Actual Behaviour**

Using `K = TypeAliasType("K", int)` fails here, whereas `K: TypeAlias = int` does not.

```python
from typing_extensions import TypeAliasType, TypeVar

K = TypeAliasType("K", int)
KeyT = TypeVar("KeyT", str, K, default=K)  # E: TypeVar default must be one of the constraint types  [misc]
```

**Expected Behavior**

No issues

**Additional information**

`no_args` is `True` for `K: TypeAlias = int`, while it is `False` for `K = TypeAliasType("K", int)`. A quick test indicates that commenting out `and not pep_695` here prevents the error from occurring.

https://github.com/python/mypy/blob/4fb187f4054f3ee1f2d585320ebe7a8876b65151/mypy/semanal.py#L4048-L4058

The effect of `no_args = False` causes the constraints of `KeyT` to be evaluated as a `TypeAliasType` instead of being evaluated to an `Instance`, 

https://github.com/python/mypy/blob/4fb187f4054f3ee1f2d585320ebe7a8876b65151/mypy/typeanal.py#L2199-L2205

which then later causes the equality check `p_default == value` to fail:

https://github.com/python/mypy/blob/4fb187f4054f3ee1f2d585320ebe7a8876b65151/mypy/checkexpr.py#L6203-L6204

**Your Environment**

- Mypy version used: 1.15, master
- Mypy command-line flags: None
- Mypy configuration options from `mypy.ini` (and other config files): None
- Python version used: 3.9, 3.13


	# Note: with the new (lazy) type alias representation we only need to set no_args to True
	# if the expected number of arguments is non-zero, so that aliases like `A = List` work
	# but not aliases like `A = TypeAliasType("A", List)` as these need explicit type params.
	# However, eagerly expanding aliases like Text = str is a nice performance optimization.
	no_args = (
	isinstance(res, ProperType)
	and isinstance(res, Instance)
	and not res.args
	and not empty_tuple_index
	and not pep_695
	)

	if max_tv_count == 0 and act_len == 0:
	if no_args:
	assert isinstance(node.target, Instance) # type: ignore[misc]
	# Note: this is the only case where we use an eager expansion. See more info about
	# no_args aliases like L = List in the docstring for TypeAlias class.
	return Instance(node.target.type, [], line=ctx.line, column=ctx.column)
	return TypeAliasType(node, [], line=ctx.line, column=ctx.column)

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Type variable defaults aren't checked properly against `TypeAliasType(...)` aliases #18862

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	if e.values and not any(p_default == value for value in e.values):
	self.chk.fail("TypeVar default must be one of the constraint types", e)

Uh oh!

Type variable defaults aren't checked properly against TypeAliasType(...) aliases #18862

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Type variable defaults aren't checked properly against `TypeAliasType(...)` aliases #18862