fix: prevent StackOverflow on self-referencing types and remap lambda receiver

[wilmveel]

Summary

• Add cycle detection (visited set) to resolveConstructorFields and resolvePropertyFields in the FIR checker to prevent StackOverflowError when types reference themselves (e.g. data class Node(val parent: Node?))
• Remap the TO extension receiver ($this$mapper) in the IR visitor to prevent dangling IR references when nested lambdas (e.g. .map {}) implicitly capture it
• Add tests for self-referencing types, nested lambdas in mapper blocks, and value class auto-mapping in DSL blocks

Test plan

• shouldCompile_selfReferencingType — verifies Category(parent: Category?) no longer causes StackOverflow
• shouldCompile_nestedLambdaInMapperBlock — verifies .map { tag -> tag.uppercase() } inside mapper lambda compiles and runs correctly
• shouldCompile_valueClassAutoMapInDslBlock — verifies value class unwrapping works with explicit DSL mappings
• shouldCompile_valueClassAutoMapInDslBlockWithSerializable — same with @Serializable target
• All existing tests pass

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