fix(server): a WS board subscriber bootstraps the current board

[EdmondDantes]

What

TODO item 1b. Over the WebSocket transport, a client that subscribes to a board room (project/{key}/issues) received nothing — it could not arrive at a correct board from subscribe alone.

• wsSubscribe() replayed the journal only for a run-trace topic (project/{key}/run/{id}/trace); a board topic fell through the regex and returned having sent nothing.
• broadcastBoards() diffs against a $sent cursor that is server-global, not per-connection — so an issue unchanged since the server last published it is never re-sent, and a room a client joins later never receives it.

The SSE stream doesn't have this bug because its $sentSnapshots cursor is a per-connection local, so its first tick dumps the whole board to each new subscriber.

Fix

On a board subscribe, dump the current board to that socket — the same first-tick dump SSE does, now available to WS. subscribe stays first so nothing published mid-dump is lost; the client keys by issue id, so the overlap with broadcastBoards' next tick is idempotent.

Verified live

No unit test — this surface has none and needs the server extension (TrueAsync\HttpServer + WebSocket). Verified with a minimal WS client against a running server: subscribing to a project's board room now delivers one {"kind":"issue","data":{…}} frame per current issue immediately, where before it delivered nothing until an issue changed.

-- upgraded --
frame 1: {"topic":"project/…/issues","kind":"issue","data":{"id":3,…}}
frame 2: {"…","kind":"issue","data":{"id":4,…}}
…                                          (the full current board, on subscribe)

Left for TODO 1d

The residual ordering — a stale snapshot value racing a concurrent change delivered on the same socket during the sub-millisecond dump — is what 1d's per-message cursor/version closes (boards have no seq to de-dupe by, unlike traces). This change is strictly better than the current "nothing sent" and introduces no new bug; the board self-corrects on the issue's next change.

Checks

composer qa green — cs, PHPStan level 8, Testo (463 tests, unchanged: no test covers this WS path).