price-trends: add sale-frequency data (how often drives discount)

Per-model and weekly computed figures: how often each current 8TB+ drive
goes on sale (best price 5%+ below its own rolling-median baseline) and how
deep. NAS lines discount several times more often than enterprise; similar
depth. Computed values only, compiled from Amazon price history.

price-trends/sale-frequency-weekly.csv

@@ -0,0 +1,117 @@
+week_start,consumer_pct_days_on_sale,enterprise_pct_days_on_sale
+2024-07-01,0,0
+2024-07-08,10.9,0
+2024-07-15,13.4,1.9
+2024-07-22,7.6,1.4
+2024-07-29,10.1,1
+2024-08-05,0.8,0
+2024-08-12,10.1,0
+2024-08-19,15.1,3.6
+2024-08-26,0,4
+2024-09-02,8,1.7
+2024-09-09,22,6.5
+2024-09-16,10.1,9
+2024-09-23,2.5,2.5
+2024-09-30,8.2,2.1
+2024-10-07,10.3,3.4
+2024-10-14,11.9,7.1
+2024-10-21,19.8,4.5
+2024-10-28,15.1,1.8
+2024-11-04,13.5,0.9
+2024-11-11,4.1,0
+2024-11-18,21.8,3.1
+2024-11-25,25.6,4.3
+2024-12-02,10.5,0.8
+2024-12-09,10,5.9
+2024-12-16,4.8,4.2
+2024-12-23,0.8,0.4
+2024-12-30,2.4,2.2
+2025-01-06,13.1,1.8
+2025-01-13,7.4,1.7
+2025-01-20,10.3,2.9
+2025-01-27,19,3.3
+2025-02-03,4,0
+2025-02-10,7.1,0
+2025-02-17,14.3,1.6
+2025-02-24,9.2,2.4
+2025-03-03,8.7,6.1
+2025-03-10,0,2.3
+2025-03-17,2.2,0
+2025-03-24,5.9,1.2
+2025-03-31,21.7,4.2
+2025-04-07,13.1,2.7
+2025-04-14,8.8,1.5
+2025-04-21,8.1,1.1
+2025-04-28,7.1,1.9
+2025-05-05,5.2,1.1
+2025-05-12,9.1,0
+2025-05-19,8.4,3
+2025-05-26,3.9,4.5
+2025-06-02,11.7,4.1
+2025-06-09,3.9,2.2
+2025-06-16,5.3,1.1
+2025-06-23,3.9,4.8
+2025-06-30,14.3,5.5
+2025-07-07,24.5,2.9
+2025-07-14,8.3,1.1
+2025-07-21,10.6,2.6
+2025-07-28,21.4,3.8
+2025-08-04,6.8,3.8
+2025-08-11,3.8,1.9
+2025-08-18,9.7,2.6
+2025-08-25,11.8,1.1
+2025-09-01,5.6,1.5
+2025-09-08,8.2,0.7
+2025-09-15,7.4,0
+2025-09-22,5.2,1.1
+2025-09-29,5.6,2.3
+2025-10-06,11.4,4.2
+2025-10-13,8.2,4.8
+2025-10-20,13.8,4
+2025-10-27,18.8,2.9
+2025-11-03,14.9,2.9
+2025-11-10,6.3,2.5
+2025-11-17,17.5,4.3
+2025-11-24,22.8,1.1
+2025-12-01,12.4,6.1
+2025-12-08,12.8,9.6
+2025-12-15,17.3,3.3
+2025-12-22,18.5,1.8
+2025-12-29,7.5,0.7
+2026-01-05,5.8,3.7
+2026-01-12,20.8,4.8
+2026-01-19,8.5,3
+2026-01-26,12.6,5.5
+2026-02-02,12.5,6
+2026-02-09,7.4,3.3
+2026-02-16,3.5,4.8
+2026-02-23,4.5,11.4
+2026-03-02,10.1,4.6
+2026-03-09,7.2,0.9
+2026-03-16,6.7,2.1
+2026-03-23,13.1,5.2
+2026-03-30,20,7
+2026-04-06,9,5.9
+2026-04-13,25,8.6
+2026-04-20,19.3,2.9
+2026-04-27,7.5,0.8
+2026-05-04,9.8,2.8
+2026-05-11,14.9,7.1
+2026-05-18,13.6,8.7
+2026-05-25,8.4,4.7
+2026-06-01,15.1,10.5
+2026-06-08,22.4,12.4
+2026-06-15,21.8,12.5
+2026-06-22,7.5,8.1
+2026-06-29,8.3,9.8
+2026-07-06,5.1,8.8
+2026-07-13,15.3,3.7
+2026-07-20,17.5,3.5
+2026-07-27,5.7,0
+2026-08-03,8.9,3.7
+2026-08-10,9.4,2
+2026-08-17,7.9,0.8
+2026-08-24,3.9,2.8
+2026-08-31,8.4,2.8
+2026-09-07,12.1,0.8
+2026-09-14,0,0