Compute average revenue per eligible day and add stock-adjustment history

[IanTheMitten]

Motivation

• Provide an availability-aware ranking of products by computing average revenue per eligible day (exclude weekends and no-transaction days and days where a product was fully out of stock).
• Reconstruct per-product day-level stock using sales + adjustment events so eligibility reflects historical inventory, not just current snapshot.

Description

• Refactored RevenueByProductTable to compute productAvgRevenuePerDay = productRevenueOnSampledDays / eligibleDaysForThatProduct, where sampled days are weekday transaction days only and results are sorted by average revenue per eligible day, showing top 10 by default with a Show all / Show top 10 toggle in the header.
• Reconstructed stock timelines from both sales (negative deltas derived from full transaction history) and explicit stock adjustments (positive/negative deltas), and implemented computeEligibleDaysForProduct to count eligible days excluding days with zero stock for the full day.
• Added persistent stock_adjustments IndexedDB store and API surface: bumped DB version to 3, added getAllStockAdjustments in localDb and productsAPI.getStockAdjustments, loaded adjustments on startup into app state, and persisted adjustment records when calling productsAPI.adjustStock.
• Wired BudgetPage -> RevenueByProductTable to pass both filtered transactions (for sampled revenue) and full transaction history + stockHistory (for reconstructing stock) while preserving existing currency and table styling conventions.

Testing

• Built the app with npm run build and the production build completed successfully.
• No unit tests were added; the change was validated by a successful production build.

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Codex Task