fix(report-summary): multiply Developer Proceeds by Units in sales summary

[gonzalobandeira]

Summary

Fixes a bug in ReportSummary.salesSummary (and the symmetric path in subscriberSummary) where Developer Proceeds was summed without multiplying by Units, causing total proceeds to be undercounted by a factor equal to the average Units-per-row.

The bug

Apple's SALES report aggregates transactions by [Country Code, Product Type, Customer Price, ...], producing rows like:

Country	Currency	Units	Customer Price	Developer Proceeds
FR	EUR	41	1.99	1.41
GB	GBP	10	0.99	0.70

Developer Proceeds is the per-unit amount the developer receives. The row's contribution to total proceeds is Units × Developer Proceeds, not Developer Proceeds alone.

The current code on develop (ReportSummary.swift:52 and :68):

let proceeds = Double(row["Developer Proceeds"] ?? "") ?? 0.0
if !currency.isEmpty {
    proceedsByCurrency[currency, default: 0.0] += proceeds   // ← missing × units
}

Impact

Real-world example from an app with ~$650 in monthly proceeds:

	Tool reports (buggy)	Actual
Total proceeds (USD eq.)	$114.63	$651.67

About 5.7× undercount. The factor depends on the average Units-per-row in the dataset, which is roughly proportional to a row's homogeneity — e.g. a single price tier in one country with many sales will have very high Units, magnifying the undercount.

The bug is not visible to anyone who only looks at total_units, by_product_type, or top_countries (those use units correctly). It only affects proceeds_by_currency (both top-level and inside each by_app entry).

The fix

In salesSummary:

let proceedsPerUnit = Double(row["Developer Proceeds"] ?? "") ?? 0.0
let rowProceeds = proceedsPerUnit * Double(units)
proceedsByCurrency[currency, default: 0.0] += rowProceeds

Same treatment applied to the per-app accumulator (appStats[...].proceedsByCurrency) and to subscriberSummary for symmetry (SUBSCRIBER rows are typically Units=1, so this is mostly defensive).

financialSummary is not affected — it uses Partner Share, which Apple already provides as the row total.

Tests

• salesSummary_proceedsByCurrency: previously asserted the buggy values (it summed per-unit amounts, which made the test pass even though the production behaviour was wrong). Updated to assert Units × Developer Proceeds.
• New salesSummary_proceedsScalesWithUnits: regression test with a single Units=100 row that would catch any reintroduction of the bug.
• New salesSummary_perAppProceedsScalesWithUnits: same regression for the by_app path.

All 24 tests in ReportSummary Tests pass on this branch (swift test --filter ReportSummaryTests).

How to verify against real data

After applying this fix and calling analytics_sales_report with summary_only: true, the proceeds_by_currency should now match what you get by manually computing sum(Units × Developer Proceeds) per currency from the raw rows (which is also what App Store Connect's "Sales and Trends" dashboard displays in your home currency, modulo FX).