Decimals in DataFrame() with orient="row" result in nulls

[ElisabethBrockhausQC]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

print(
    pl.DataFrame(
        schema={"a": pl.Int64, "b": pl.Decimal(scale=2)},
        data=[
            (1, 1.0),
            (2, 2.0),
            (3, 3.0),
        ],
        orient="row",
    )
)
# output:
# shape: (3, 2)
# ┌─────┬──────────────┐
# │ a   ┆ b            │
# │ --- ┆ ---          │
# │ i64 ┆ decimal[*,2] │
# ╞═════╪══════════════╡
# │ 1   ┆ null         │
# │ 2   ┆ null         │
# │ 3   ┆ null         │
# └─────┴──────────────┘

Log output

Issue description

When using the pl.Decimal() dtype in the schema of a DataFrame with orient="row", the column contains only null values.

Expected behavior

In the given example, the DataFrame should look like

# shape: (3, 2)
# ┌─────┬──────────────┐
# │ a   ┆ b            │
# │ --- ┆ ---          │
# │ i64 ┆ decimal[*,2] │
# ╞═════╪══════════════╡
# │ 1   ┆ 1.00         │
# │ 2   ┆ 2.00         │
# │ 3   ┆ 3.00         │
# └─────┴──────────────┘

Installed versions

--------Version info---------
Polars:              1.23.0
Index type:          UInt32
Platform:            macOS-15.3.1-arm64-arm-64bit
Python:              3.12.8 | packaged by conda-forge | (main, Dec  5 2024, 14:19:53) [Clang 18.1.8 ]
LTS CPU:             False

----Optional dependencies----
Azure CLI            <not installed>
adbc_driver_manager  <not installed>
altair               5.5.0
azure.identity       <not installed>
boto3                1.36.14
cloudpickle          3.1.1
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               2025.2.0
gevent               <not installed>
google.auth          2.38.0
great_tables         <not installed>
matplotlib           <not installed>
numpy                <not installed>
openpyxl             3.1.5
pandas               <not installed>
polars_cloud         <not installed>
pyarrow              <not installed>
pydantic             2.10.6
pyiceberg            <not installed>
sqlalchemy           2.0.38
torch                <not installed>
xlsx2csv             <not installed>
xlsxwriter           3.2.2```

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