Memoize dashboard and history table columns

Docs/Tasks.md

@@ -128,7 +128,7 @@ Issues are grouped by category and ordered roughly by severity. Each entry descr
 
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-### TASK-007 — Setup page password validation too weak
+### TASK-007 — Setup page password validation too weak (done)
 
 **Where found:** `frontend/src/pages/SetupPage.tsx`, `validate()` function. Only `masterPassword.length < 8` is checked.
 
@@ -148,7 +148,9 @@ Issues are grouped by category and ordered roughly by severity. Each entry descr
 
 ---
 
-### TASK-008 — `buildBanColumns` and `HISTORY_COLUMNS` recreated on every render
+### TASK-008 — `buildBanColumns` and `HISTORY_COLUMNS` recreated on every render (done)
+
+**Where fixed:** `frontend/src/components/BanTable.tsx`, `frontend/src/pages/HistoryPage.tsx`
 
 **Where found:**
 - `frontend/src/components/BanTable.tsx` — `buildBanColumns(styles)` called unconditionally in the render body.