text: Title: Subclassing generic dataclass loses type of parent class fields
  Body: ### Initial Checks
  
  - [x] I confirm that I'm using Pydantic V2
  
  ### Description
  
  This might be a non-issue if dataclasses are not intended to be subclassed.
  
  When extending a generic dataclass, the fields from the superclass have no validation done on them.
  
  ```python
  @dataclass
  class A(Generic[T]):
      a: T
  
  @dataclass
  class B(A[U]):
      b: U
  ```
  
  I would expect here that deserialising something to `B[int]` would validate that `a` was an `int` but this doesn't appear to happen.
  
  ### Example Code
  
  ```Python
  from pydantic.dataclasses import dataclass
  from pydantic import TypeAdapter
  from typing import TypeVar, Generic
  
  T = TypeVar('T')
  U = TypeVar('U')
  
  @dataclass
  class A(Generic[T]):
      a: T
  
  @dataclass
  class B(A[U]):
      b: U
  
  b = TypeAdapter(B[int]).validate_python({"a": ["not", "an", "int"], "b": "42"})
  #                       ^^^^^^^^^^^^^^^
  # This does not fail even though the type of a is not valid
  
  print(b)
  
  assert b.b == 42 # <- Passes as "42" has been converted to an int correctly
  assert type(b.a) == int # <- This fails as a is a list
  ```
  
  ### Python, Pydantic & OS Version
  
  ```Text
  pydantic version: 2.10.6
          pydantic-core version: 2.27.2
            pydantic-core build: profile=release pgo=false
                   install path: /path/to/.venv/lib/python3.12/site-packages/pydantic
                 python version: 3.12.7 (main, Oct  8 2024, 00:20:25) [Clang 18.1.8 ]
                       platform: Linux-6.6.72-1-lts-x86_64-with-glibc2.40
               related packages: pydantic-settings-2.7.1 fastapi-0.115.7 pyright-1.1.392.post0 typing_extensions-4.12.2
                         commit: unknown
  ```