Make an absent chiamata bidder pass instead of bidding randomly

The auction timeout bid a random legal rank, which could hand the
auction (and the call) to a disconnected player. An absent bidder now
always passes; only the last player standing before any bid cannot
pass, and is made to bid the ace - its suit is picked at random by the
existing call timeout. This keeps a deal from stalling without a caller
while never letting an absent player outbid someone.

The deadline log line now says which of the two happened.

server/README.md

@@ -375,9 +375,9 @@ timeout is `TURN_TIMEOUT_SECONDS` (default 30); the auto-played move is
 broadcast like any other. Deadlines fire from the shared `tavolo:deadlines`
 queue (see above), not from timers tied to client connections, so the
 match keeps progressing even with every player disconnected. Briscola
-chiamata uses the same timeout for its auction bids (auto-bid or
-auto-pass) and for the called-card choice (a random suit of the won
-rank).
+chiamata uses the same timeout for its auction turns (an absent bidder
+passes; the last player standing with no bid is made to bid the ace) and
+for the called-card choice (a random suit of the won rank).
 
 ### Hand-end summary
 
@@ -460,9 +460,10 @@ player must dismiss. A play attempted in this phase is rejected with an
   replayed with the next dealer. A match is a single deal, so the caller
   and partner (or the lone caller) against the other players map onto
   the platform's two-team result, Elo and history.
-- Auction bids, the called-card choice and the plays all have their own
-  `TURN_TIMEOUT_SECONDS` deadlines (an absent player is auto-bid,
-  auto-called or auto-played for).
+- Auction turns, the called-card choice and the plays all have their own
+  `TURN_TIMEOUT_SECONDS` deadlines: an absent bidder passes, the last
+  player standing with no bid is made to bid the ace, an absent winner's
+  call names a random suit of the won rank, and plays are auto-played.
 
 ## Development