Fresh UI: add typed DataGrid multi-select, bulk actions, and per-row action menu

[rickylabs]

Problem

Applications using @netscript/fresh-ui need a reusable data-grid/list pattern for managing collections. eis-chat now has the same requirement on both Knowledge Base assets and channel sessions, but its local DataGrid only supports a single selected row plus onSelect/href.

Requested API / behavior

• controlled multi-selection (selectedIds, select row, select all, indeterminate header)
• accessible keyboard and screen-reader semantics for checkboxes and rows
• bulk-action toolbar slot with selection count
• per-row actions slot/menu (for example Rename, Archive, Delete, Reprocess)
• destructive action styling and disabled/loading states
• event isolation so checkbox/menu clicks do not trigger row navigation
• responsive behavior for narrow layouts
• typed generic row/column API compatible with Fresh/Preact

Concrete consumers

1. KB documents: bulk Delete/Reprocess, rename, labels, OCR provenance.
2. Channel sessions: bulk Archive/Delete and per-row Rename/Archive/Delete menu.

Acceptance criteria

A consumer should not need to hand-roll selection state, select-all logic, keyboard behavior, menu event propagation, and bulk-toolbar layout for every grid. Include a reference example and tests for selection + row actions.

Current workaround

eis-chat/apps/dashboard/components/blocks/data-grid.tsx is being extended locally to unblock product work; it should migrate to the shared Fresh UI primitive once available.

[rickylabs]

Additional acceptance criterion found during implementation: every per-row action menu/listbox must light-dismiss on outside pointer interaction, close on Escape, and close after selecting an option. This should be owned by the shared Fresh UI primitive (including focus restoration), not reimplemented per consumer. eis-chat currently carries a scoped document-level fallback for menu/listbox disclosures until the shared component provides this behavior.

[rickylabs]

Additional API requirement: a list/DataGrid row must be type-safely linkable as a whole while still allowing nested selection and action controls. The shared primitive should accept a typed route/href (or navigation callback), support Enter/Space and client navigation, and exclude checkbox/menu/button activation without producing invalid nested interactive HTML (for example, buttons inside an anchor). The current eis-chat workaround uses a row activation handler plus a real title-link fallback.