Add "Migrating from Pandas" guide

[zaleslaw]

It's a draft, should be shipped with the validated Pandas / Kotlin DataFrame code

[Copilot]

Pull Request Overview

This PR adds a migration guide for Pandas users moving to Kotlin DataFrame and tidies up navigation and formatting.

• Introduces a new “Migrating from Pandas” guide
• Cleans up a formatting quirk in the Quickstart guide
• Updates the documentation tree to include the new guide

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/StardustDocs/topics/guides/quickstart.md	Merged two bullet lines into a single paragraph and added spacing
docs/StardustDocs/topics/guides/migratingFromPandas.md	Added the full migration guide from Pandas to Kotlin DataFrame
docs/StardustDocs/d.tree	Inserted the new guide into the site’s table of contents

Comments suppressed due to low confidence (2)

docs/StardustDocs/topics/guides/migratingFromPandas.md:214

• [nitpick] Wrap technical terms and function names such as advanced time indexing and resample() in backticks for inline code formatting to improve readability.

- Some Pandas features (like advanced time indexing, resample()) aren’t available yet.

docs/StardustDocs/topics/guides/migratingFromPandas.md:1

• [nitpick] Consider renaming the file to use kebab-case (e.g., migrating-from-pandas.md) to match the naming convention of other guide files.

# Migration Guide: Pandas to Kotlin DataFrame

[Copilot]

Remove the trailing whitespace at the end of this line to avoid unintended formatting or layout issues.

Suggested change

	everything works out of the box, including interactivity and rich DataFrame and plots rendering.
	everything works out of the box, including interactivity and rich DataFrame and plots rendering.

[AndreiKingsley]

@zaleslaw may be use tabs instead of subsequent paragraphs (like polars docs do)?

Instead of

### Pandas (Matplotlib)

```python
df["profit"] = df.revenue - df.cost
pivot = df.pivot_table(values="profit", index="product", columns="year")
```

### Kotlin DataFrame (Kandy)

```kotlin
val pivot = df
    .add("profit") { revenue - cost }
    .pivot(product, year) { mean(profit) }
```

add tabs:

<tabs>
    <tab title="Pandas (Matplotlib)">
        ```python
df["profit"] = df.revenue - df.cost
pivot = df.pivot_table(values="profit", index="product", columns="year")
```
</tab>
    <tab title="Kotlin DataFrame (Kandy)">
       ```kotlin
val pivot = df
    .add("profit") { revenue - cost }
    .pivot(product, year) { mean(profit) }
```
</tab>

</tabs>

in all such places.

[zaleslaw]

The guide is useful, but I would not merge it before validating the code snippets. A few examples currently look non-compilable against the current API:

• DataFrame.readArrow(...) / writeArrow(...) should likely be readArrowFeather/readArrowIPC and writeArrowFeather/writeArrowIPC.
• DataFrame.readSqlTable("table", jdbcUrl) does not match current overloads; the first argument should be DbConnectionConfig, DataSource, or Connection.
• df.na.count() looks like Pandas syntax and I could not find a matching Kotlin DataFrame API; describe() exposes nulls.
• df1.join(df2, by = "id") should be df1.join(df2, "id") or selector syntax; for left join, consider df1.leftJoin(df2, "id").

Since the PR description says this should be shipped with validated Pandas / Kotlin DataFrame code, I’d suggest moving representative snippets into sample functions and referencing them with <!---FUN ...--> blocks before publishing the guide.