Release Notes:

- Fixed injected language highlighting for strings containing
interpolations

current             |  updated
:-------------------------:|:-------------------------:

![](https://github.com/user-attachments/assets/b1e609c4-f0cd-45af-9e11-abcc711a19ea)
|
![](https://github.com/user-attachments/assets/9d6eb37e-f476-4495-bcec-9792ad52d3d6)

<details>

<summary> test snippet  </summary>

```python
my_regex = r"[0-9]"
spark.sql(  # sql
    f"""
        SELECT
            col1,
            CASE WHEN col2 RLIKE '{my_regex}' THEN '1' ELSE '2' END col4,
            ROW_NUMBER() OVER(PARTITION BY col1, col2 ORDER BY col3) as rn
        FROM tbl
    """
)
```

</details>

## Summary
Strings with interpolations like `f"SELECT col1 FROM tbl WHERE col2 =
'{my_var}'"` in Python produce multiple `string_content` nodes. Without
grouping, each fragment gets its own injection layer which breaks syntax
highlighting.

This PR adds an `@injection.host` capture to group `@injection.content`
ranges by their host node. This was implemented by extending the
existing `combined_injection_ranges` hash map with a node key per host.
Added tests for this behavior covering simple strings, f-strings with
single/multiple interpolations, and multi-string isolation.

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>