strengthen pyright detection

[robin523790]

import construct as cs
import construct_typed as cst

@dataclasses.dataclass
class MyClass(cst.DataclassMixin):
    my_param: bytes = cst.csfield(cs.Bytes(30), doc="""test""")

c = MyClass()

Above code did not trigger a Pyright error but failed at runtime.

This PR introduces @overloads to csfield() that allow Pyright to ensure that:

• fields that are not provided now raise errors
• Const fields that are provided now raise errors (as these must only be provided in the declaration)
• Default fields can be provided but do not have to (as the default value may be overriden)

This PR includes the migration to uv and the version bump to 0.8.0 found here: #37.

BREAKING CHANGES
This PR introduces breaking changes, thus the version has been bumped to 0.8.0.

• Default fields are only treated as optional if they have an explicit (and redundant) default= marker. A wrapper method csdefault_field() has been provided for convenience.

class MyClass(cst.DataclassMixin):
    my_default_1: bytes = cst.csfield(cs.Default(cs.Bytes(30), bytes(30)), doc="""test""", default=bytes(30))
    my_default_2: bytes = cst.csdefault_field(cs.Bytes(5), bytes(5), doc="""test""")

• Any fields following a Default field must have the kw_only= marker and must be provided by keyword.

class MyClass(cst.DataclassMixin):
    my_default: bytes = cst.csdefault_field(cs.Bytes(30), bytes(30), doc="""test""")
    my_param: bytes = cst.csfield(cs.Bytes(5), doc="""test""", kw_only=True)

c1 = MyClass(b"Hello")  # WRONG
c2 = MyClass(my_param=b"World")  # correct

[Copilot]

Pull request overview

This PR strengthens static type checking (Pyright) around construct_typed dataclass fields by refining typing behavior for csfield()/Default/Const/Computed patterns, aiming to prevent cases that previously passed type checking but failed at runtime.

Changes:

• Added a set of @overload signatures for csfield() and introduced csdefault_field() to better model Default-field optionality and forbidden init parameters for Const/Computed/Pass-like constructs.
• Updated Construct stubs to improve typing for Computed and singleton constructs (Tell, Pass, Terminated) used by the new overloads.
• Expanded/adjusted tests to cover Default/Computed/Padded behavior and updated expected values accordingly.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
tests/test_typed.py	Updates/adds tests intended to validate Pyright behavior for const/default/computed/padded fields.
construct-stubs/core.pyi	Refines stub typing for Computed and makes Tell/Pass/Terminated usable as distinct singleton types.
construct_typed/dataclass_struct.py	Adds overload-driven typing for csfield() and adds csdefault_field() to model Default-field semantics.
construct_typed/__init__.py	Exports csdefault_field from the package API.

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[robin523790]

@timrid This looks bogus to me. What do you think?