duckdb sniff_csv fails with > 10240 lines

### What happens?

When I use sniff_csv implicitly using read_csv with the arguments ", header=True, delim=';', sample_size=10241", it triggers an "unable to detect csv format"-error.

- I can place multiple different lines on line 20241 and they all trigger it. The lines seem fine and not different than any others.
- When I reduce the sample_size to 10240, the import works again.
- When I then remove lines 10236-10240 from the original file and keep the sample_size on 10240, it also works.

This indicates to me that 10240 is an upper limit for the sampling before it goes wrong, but the default is of 20xxx.

I unfortunately can't provide you the sample.

The duckdb-version is "v1.2.0"

### To Reproduce

```
self._db.execute(f"CREATE OR REPLACE TABLE {all_table_name} AS SELECT * FROM read_csv('{self.event.tmp_file_path}', header=True, delim=';', sample_size=10241)")
```

### OS:

Linux

### DuckDB Package Version:

1.2.0

### Python Version:

3.13.7

### Full Name:

Michel

### Affiliation:

Acme

### What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

I have tested with a stable release

### Did you include all relevant data sets for reproducing the issue?

No - I cannot share the data sets because they are confidential

### Did you include all code required to reproduce the issue?

- [x] Yes, I have

### Did you include all relevant configuration to reproduce the issue?

- [x] Yes, I have

提供されている Python execute 呼び出しを、read_csv、header=True、delim=';'、および sample_size の値 10240 と 10241 を使って開始します。10240 行を超えてサンプリングすると sniff_csv が失敗する理由を調査します。完了条件は、より大きな sample_size 値で再現時に "unable to detect csv format" エラーが発生しなくなることです。

索引モデルが issue の本文から書いたものです。