fix: improve type resolution for model field declarations (#2216)

* fix: improve type resolution for model field declarations

* Updated model field declarations to resolve to their concrete types (e.g., `CharField[str]`) in Pyright/Pylance, enhancing type-checking accuracy.
* Modified the `Field.__new__` type-check stub to return `Self`, improving type inference.

This change addresses type-checking issues and improves developer experience with IDEs.

* Update CHANGELOG with reference to the issue

Author: vlakius

CHANGELOG.rst

@@ -22,6 +22,7 @@ Fixed
 ^^^^^
 - ``MigrationRecorder`` now uses parameterized queries; fixes MariaDB/MySQL rejecting ISO-8601 ``applied_at`` values. (#2132)
 - ``QuerySet.count()`` now matches the limited query result for the LIMIT/OFFSET edge cases: it returns ``0`` (instead of a negative number) when ``offset()`` exceeds the total row count, and ``0`` (instead of the total) for ``limit(0)``. (#2208)
+- Field declarations on models now resolve to their concrete type (e.g. ``CharField[str]``) in Pyright/Pylance instead of ``Field[Unknown]``; the ``Field.__new__`` type-check stub now returns ``Self``. (#2216)
 
 1.1.7
 -----

tortoise/fields/base.py

@@ -19,7 +19,9 @@
 
 if sys.version_info >= (3, 11):
     from enum import StrEnum
+    from typing import Self
 else:  # pragma: no cover
+    from typing_extensions import Self
 
     class StrEnum(str, Enum):
         __str__ = str.__str__
@@ -202,7 +204,7 @@ def function_cast(self, term: Term) -> Term:
     # These methods are just to make IDE/Linters happy:
     if TYPE_CHECKING:
 
-        def __new__(cls, *args: Any, **kwargs: Any) -> Field[VALUE]:
+        def __new__(cls, *args: Any, **kwargs: Any) -> Self:
             return super().__new__(cls)
 
         @overload