The dependency graph's canPathBeArray() analysis incorrectly reports that fields produced by N-style accumulators ($minN, $maxN, $firstN, $lastN, $topN, $bottomN) cannot contain arrays. These accumulators always emit an array of length n, so any field they assign is always an array.

This was detected by the new aggregation_dependency_graph_validation_passthrough suite (SERVER-125083) running [group_pbt.js, which inserts $_internalAssertDataAssumptions stages between pipeline stages to validate the analysis at runtime.

Steps to Reproduce

Run with internalEnableDependencyGraphValidation: true, featureFlagEnableTestingAggregateRewriteRules: true, featureFlagPathArrayness: true:

db.coll.drop();
db.coll.insert({_id: 0, a: 1});
db.coll.aggregate([
{$group: {_id: null, m: {$minN: {input: "$a", n: 1}}}},
{$project: {"m.m2": "$a"}},
{$unwind: {path: "$m"}},
{$project: {_id: 0, a: 1}}
]);

Expected Behavior

The aggregation runs successfully. The dependency graph reports that m can be an array after [$group.

Actual Behavior
Location12508302: Dependency graph arrayness validation failed: field 'm'
contains an array but canPathBeArray() returned false.
Document: {_id: null, m: [{}]}.
This indicates a bug in the dependency graph analysis.

The intermediate document {_id: null, m: [{}]} produced by $group has m as an array ($minN always returns an array of size n), but the dependency graph's arrayness tracker reports canPathBeArray("m") == false, causing the runtime validator to fire.

Root cause. The arrayness analysis for accumulator output paths in $group does not account for accumulators whose output is unconditionally an array. Affected accumulators include:

$minN, $maxN
$firstN, $lastN
$topN, $bottomN
$push, $addToSet (also produce arrays — these may already be handled, but should be verified)

The analysis should mark the output field of any such accumulator as potentially-array.

Proposed fix. In the dependency graph's accumulator-output arrayness logic, set the produced path to canBeArray=true for the accumulators listed above. Add coverage in path_arrayness_test.cpp for each accumulator.