[TypeDeclarationDocblocks] Fix invalid array-in-key docblock when narrowing long array unions

[TomasVotruba]

Fixes rectorphp/rector#9865

ClassMethodArrayDocblockParamFromLocalCallsRector could emit an invalid docblock with an array type in the array-key slot, e.g. @param array<mixed[], mixed> $data.

Cause

When a resolved param type is a union of arrays whose printed form exceeds the max length, TypeNormalizer::generalizeConstantTypes() narrows it via narrowToAlwaysKnownArrayType():

$arrayUniqueKeyType = $this->arrayTypeLeastCommonDenominatorResolver->sharedArrayStructure(...);
return new ArrayType($arrayUniqueKeyType, new MixedType());

sharedArrayStructure() already returns a full array structure (e.g. array<int, mixed>), but the code dropped it into the key slot of a new ArrayType, yielding array<array<int, mixed>, mixed> which prints as the invalid array<mixed[], mixed>. The variable name $arrayUniqueKeyType shows the structure was mistaken for a key type.

Fix

Return the shared array structure directly. The heterogeneous case from the issue now narrows to a plain mixed[], which the existing mixed-array guard skips, so no invalid docblock is written.

Added a skip_* fixture reproducing the exact case from the issue.