feat(web): adopt @vincjo/datatables for all tables, standardize shared components

- Add DataTable.svelte: declarative columns, built-in sorting, sticky headers,
  text truncation, column alignment, configurable widths, optional pagination/search
- 12 built-in renderers: BadgeRenderer, StatusBadgeRenderer (unified risk/severity/
  execution/state/type variant mapping), HealthDotRenderer, RelativeTimeRenderer,
  DateRenderer, DurationRenderer, StatusDotRenderer, SignalActions, ApprovalActions,
  ActivityAction, ActivityCancel
- Migrate Overview (task board), Signals, Ops (3 tables) to DataTable
- Refactor EntityTable treegrid to use shared SortHeader, EmptyState, HealthDotRenderer
- Create shared components: EmptyState, StatusBadge, FilterTabs
- Clean up Knowledge.svelte: replace inline relTime() and typeVariant() with shared utils
- Add width, align, truncate column props; table-fixed layout; rounded-xl borders
- Bump version to 0.11.0

web/src/lib/components/data-table/columns.ts

@@ -0,0 +1,9 @@
+import type { DataTableColumn } from './DataTable.svelte.ts'
+
+export function resolveCellValue<T>(row: T, col: DataTableColumn<T>): unknown {
+  if (col.accessor) return col.accessor(row)
+  if (col.key in (row as Record<string, unknown>)) {
+    return (row as Record<string, unknown>)[col.key]
+  }
+  return undefined
+}