improve cart recovery: product links in email, persistent session cookie

- add product_id to order_items (migration + schema + create_order)
- cart recovery email now includes a direct product link per item
- extend session cookie max_age to 7 days so carts survive browser restarts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

PROGRESS.md

@@ -91,7 +91,7 @@ Plans: [admin-redesign.md](docs/plans/admin-redesign.md) | [admin-font-loading.m
 | | **Analytics v2** ([plan](docs/plans/analytics-v2.md)) | | | |
 | ~~52~~ | ~~Comparison mode: period deltas on stat cards~~ | — | 1h | done |
 | ~~53~~ | ~~Dashboard filtering (click to filter by dimension)~~ | 52 | 3h | done |
-| 54 | CSV export | 52 | 1.5h | planned |
+| ~~54~~ | ~~CSV export~~ | 52 | 1.5h | done |
 | ~~55~~ | ~~Entry/exit pages panel~~ | — | 1h | done |
 | | **Favicon & site icons** ([plan](docs/plans/favicon.md)) | | | |
 | 86 | Favicon source upload — `image_type: "icon"`, "use logo as icon" toggle, upload in theme editor, `FaviconGeneratorWorker`, `favicon_variants` table | — | 2.5h | planned |
@@ -452,7 +452,7 @@ See: [plan](docs/plans/shipping-sync.md) for implementation details
 - [x] Period comparison deltas on stat cards (6eda1de)
 - [x] 2-year demo seed data with growth curve (6eda1de)
 - [x] Dashboard filtering (click referrer/country/device to filter all panels) (7ceee9c)
-- [ ] CSV export
+- [x] CSV export (ZIP with 12 CSVs, period + filter aware)
 - [x] Entry/exit pages panel
 
 See: [docs/plans/analytics-v2.md](docs/plans/analytics-v2.md) for v2 plan