Board: tuck per-row actions behind a ⋯ menu

The inline Edit / Re-broadcast / Delete (and Block) buttons wrapped messily in
the actions column. Replace them with a single ⋯ button per row that opens a
small popout menu with the relevant actions. Closes on outside click, Escape,
or selecting an item; the actions and their data-act wiring are unchanged.

Adds the menu markup/toggle in board.js, an "Actions" aria-label string × 14
languages, and menu/kebab styles. e2e updated to open the menu before acting.
234 e2e across all six engines.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

docs/nostr-static-client-spec.md

@@ -276,7 +276,8 @@ de-duplicated per author+`d` identifier, keeping the latest.
   link).
 - The npub column is forward-looking — anonymous keys today, but a stable
   identity per author maps cleanly onto this view later.
-- **Per-row actions.** On flyers the connected viewer authored, the board shows
+- **Per-row actions** (behind a per-row **⋯ menu**). On flyers the connected
+  viewer authored, the menu offers
   **Edit** (a link to `/?edit=1#<naddr>`, which loads the flyer in the editor),
   **Re-broadcast** (re-sends the already-signed event to all relays — no signing
   needed), and **Delete** (tombstone + NIP-09; the board signs via the device