v5.0.0: protocol v5 and the browser frontend

Protocol v5 replaces newline lines with bounded [u32 len][text] frames and REQ/RES/EVT envelopes. Requests carry correlation ids and the server replays the last 256 replies per connection, so a gateway retry cannot double-debit and a late reply cannot clobber a newer request. HELLO/PONG carry server time; crash rounds announce started_at and push coalesced 10 Hz ticks. Crash now commits sha256(seed) before a round and reveals the seed when it ends, so clients recompute the crash point.

Adds the webd/ gateway: one blocking thread, one ClientCore and one pinned upstream TLS connection per session, an HttpOnly session cookie, takeover, and a 60-second grace window. The browser sends Command JSON and renders View JSON; it never speaks the game protocol or stores credentials.

Adds the vanilla TypeScript browser app at /play/ (login, lobby, all four games, history, notices, crash verification), the nginx /play and /ws routes, and the headless DOM smoke test. webd and the app stay out of the TUI/GUI/server build graph.

The client/server version moves to 5.0.0 in lockstep; v4 peers are refused at HELLO.

1 files changed, 1 insertions, 0 deletions

diff --git a/web/index.php b/web/index.php
index 3f0ab92..b03eac6 100644
--- a/web/index.php
+++ b/web/index.php
@@ -58,6 +58,7 @@ function human_size(int $bytes): string
 <body>
 
 <h1>żagań.bet</h1>
+<p><a href="<?= e($base) ?>/play/"><strong>Play in your browser</strong></a> — no install, just an account. Play-money only.</p>
 <p>Official desktop app, terminal client and server builds.</p>
 <?php if ($newest > 0): ?>
 <p>Builds published <?= e(gmdate('j M Y H:i', $newest)) ?> UTC.</p>