feat(pivotp): expand smart aggregation with 7 more statistics

[jqnatividad]

Summary

• Expand --agg smart to consult 7 additional statistics from StatsData for better aggregation decisions
• Numeric: mad_stddev_ratio, median_mean_ratio, quartile_coefficient_dispersion → Median; n_negative/n_positive mixed-sign guard → Mean; mode_count > 10 multimodal → Len
• Date/DateTime: sparsity > 50% → Len; ascending sort order → Last
• Add 7 tests covering each new signal path
• Update --agg smart help text to document all signals

Test plan

• cargo test pivotp -F all_features — all 56 tests pass (49 existing + 7 new)
• cargo clippy --bin qsv -F all_features -- -W clippy::pedantic — zero warnings
• Manual verification with crafted CSVs for each new signal (MAD/stddev divergence, median/mean divergence, QCD, mixed-sign, multimodal, sparse dates, ascending dates)

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🟢 Metrics 50 complexity

Metric	Results
Complexity	50

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[Copilot]

Pull request overview

Expands pivotp --agg smart to use additional statistics (including new moarstats-derived signals) to choose more appropriate aggregations for numeric and temporal value columns, and adds tests covering the new decision paths.

Changes:

• Enhanced smart aggregation heuristics for numeric columns (multimodality, robust-spread divergence, mean/median divergence, quartile dispersion, mixed-sign guard).
• Enhanced smart aggregation heuristics for Date/DateTime columns (sparsity and ascending sort order handling).
• Added 7 new integration tests and updated --agg smart help text to document the signals.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/cmd/pivotp.rs	Updates --agg smart help text and adds new smart-aggregation decision branches for numeric and Date/DateTime columns.
tests/test_pivotp.rs	Adds 7 tests to exercise each newly added smart-aggregation signal path.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/cmd/pivotp.rs:549

• In the Date/DateTime path, the high_cardinality_pivot || high_cardinality_index branch returns before the sort_order.starts_with("Ascending") check below. This means a value column that is globally ascending can still select First (when the pivot/index aren’t both ordered), which doesn’t match the PR description’s “ascending sort order → Last” signal. Consider checking the value column’s ascending sort_order before the high-cardinality branch, or incorporating the ascending check into that branch as well so Last is preferred whenever the temporal values are ascending.

                } else if high_cardinality_pivot || high_cardinality_index {
                    if ordered_pivot && ordered_index {
                        if !quiet {
                            eprintln!(
                                "Info: Ordered temporal data with high cardinality, using Last"