Provide metadata about DataFrame API in form of Kotlin program

This metadata can be useful both for us as a high level overview of the library and for AI agents (maybe).
"How much public API do we have?
Find me all intermediate df operations
Prepare a plan for better Java/Scala/... interop"
konsist library for scanning sources, typeOf / ::class for references.
Need to have compiler plugin configured - potentially it can be our own integration testing of dataframe and all our tooling
```
// explain multiplex operations
val intermediateClasses = setOf(typeOf(), typeOf(), typeOf())

// explain
val dataframeApiReceivers = setOf(
DataFrameOperationReceiver,...
)

val utilityReceivers = setOf(
DataFrameOperationReceiver(ColumnPath...
)

val columnSelectionDsl = ...

data class DataFrameOperationReceiver(val mainType: ..., val aliases ...)
```

Start by reviewing the Kotlin DataFrame public API and the proposed Konsist-based source scan, including the required compiler-plugin setup. Done means the metadata program's scope and output are defined for the listed API queries, with a plan for compiler-plugin integration testing.

Written by the indexing model from the issue text.