Fix Pylint messages "Attribute ... defined outside __init__"

This commit fixes the following lint warnings:

```console
$ pylint --version
pylint 4.0.4
astroid 4.0.2
Python 3.14.2 (tags/v3.14.2:df79316, Dec  5 2025, 17:18:21) [MSC v.1944 64 bit (AMD64)]

$ pylint $(git ls-files '*.py')
************* Module kaitaistruct
kaitaistruct.py:317:8: W0201: Attribute 'bits_left' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:377:8: W0201: Attribute 'bits_left' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:684:8: W0201: Attribute 'bits_left' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:718:8: W0201: Attribute 'bits_left' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:330:12: W0201: Attribute 'bits' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:372:12: W0201: Attribute 'bits' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:692:12: W0201: Attribute 'bits' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:699:12: W0201: Attribute 'bits' defined outside __init__ (attribute-defined-outside-init)
kaitaistruct.py:727:12: W0201: Attribute 'bits' defined outside __init__ (attribute-defined-outside-init)

-----------------------------------
Your code has been rated at 9.82/10
```

Author: generalmimon

kaitaistruct.py

@@ -95,7 +95,8 @@ def __setattr__(self, key, value):
 class KaitaiStream:
     def __init__(self, io):
         self._io = io
-        self.align_to_byte()
+        self.bits_left = 0
+        self.bits = 0
         self.bits_le = False
         self.bits_write_mode = False