Publish an SSE update from the bet/withdrawal rollback paths (B-49)

_release_failed_bet and _release_failed_withdrawal restored the balance, freed
the reserved UTXOs and (for a bet) removed the participant without calling
broadcaster.publish(), so every dashboard kept showing the phantom bet and the
reduced balance until its next poll — while the success path and the
reconciler's own abandon path both published.

The two regression tests pre-open the round before subscribing: place_bet opens
one itself, and that publish() would otherwise satisfy the assertion whether or
not the rollback published anything.

tests/unit/test_bets.py

@@ -8,6 +8,7 @@ from app.bets.service import BetError, place_bet
 from app.config import settings
 from app.db.base import Base
 from app.db.models import AuditLog, PendingTransaction, Round, RoundConfig, RoundParticipant, User, UtxoEvent
+from app.rounds.events import broadcaster
 from app.rounds.service import open_new_round_if_needed
 from app.wallet.hd import derive_user_address
 from app.wallet.psbt_builder import MAX_TX_INPUTS
@@ -196,6 +197,33 @@ async def test_failed_broadcast_leaves_nothing_behind(session_factory):
         assert "bet_placed" not in events
 
 
+async def test_failed_broadcast_publishes_an_sse_update(session_factory):  # B-49
+    """The rollback moves as much state as the successful path does, so it must ping
+    the dashboards the same way — otherwise the phantom bet stays on screen until the
+    next poll."""
+    user_id = await _make_funded_user(session_factory, 21, 3_000_000_000)
+    async with session_factory() as session:
+        # Open the round up front: place_bet would otherwise open it itself, and that
+        # publish() would satisfy the assertion below whether or not the rollback ever
+        # published one of its own.
+        await open_new_round_if_needed(session)
+        await session.commit()
+
+    queue = broadcaster.subscribe()
+    try:
+        while not queue.empty():
+            queue.get_nowait()
+
+        async with session_factory() as session:
+            user = await session.get(User, user_id)
+            with pytest.raises(BetError, match="refused"):
+                await place_bet(session, RejectingElectrumClient(), user)
+
+        assert not queue.empty()
+    finally:
+        broadcaster.unsubscribe(queue)
+
+
 async def test_failed_broadcast_reports_the_broadcast_failed_code(session_factory):
     user_id = await _make_funded_user(session_factory, 5, 3_000_000_000)