BUG: DataFrame.eval(engine='python') mutates original dataframe when inplace=False

[sfc-gh-mvashishtha]

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Reproducible Example

import modin.pandas as pd
df = pd.DataFrame([1], columns=['a'])
df.eval('b = a', inplace=False, engine='python')
assert 'b' not in df.columns

Issue Description

When inplace=False, we should not update the input dataframe, but we do.

Expected Behavior

We should not update the input dataframe.

Error Logs

N/A

Installed Versions

INSTALLED VERSIONS

commit : 0691c5cf90477d3503834d983f69350f250a6ff7
python : 3.9.21
python-bits : 64
OS : Darwin
OS-release : 24.6.0
Version : Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:30 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6020
machine : arm64
processor : arm
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 2.2.3
numpy : 2.0.2
pytz : 2025.2
dateutil : 2.9.0.post0
pip : 24.2
Cython : None
sphinx : 7.4.7
IPython : 8.18.1
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.13.4
blosc : None
bottleneck : None
dataframe-api-compat : None
fastparquet : 2024.11.0
fsspec : 2025.3.2
html5lib : None
hypothesis : None
gcsfs : None
jinja2 : 3.1.6
lxml.etree : 5.3.2
matplotlib : 3.9.4
numba : None
numexpr : 2.10.2
odfpy : None
openpyxl : 3.1.5
pandas_gbq : 0.28.0
psycopg2 : 2.9.10
pymysql : None
pyarrow : 18.1.0
pyreadstat : None
pytest : 8.4.0
python-calamine : None
pyxlsb : None
s3fs : 2025.3.2
scipy : 1.13.1
sqlalchemy : 2.0.40
tables : N/A
tabulate : 0.9.0
xarray : 2024.7.0
xlrd : 2.0.1
xlsxwriter : None
zstandard : None
tzdata : 2025.2
qtpy : None
pyqt5 : None