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, 43 insertions, 9 deletions

diff --git a/docs/TESTING.md b/docs/TESTING.md
index 09ceb82..fbd510b 100644
--- a/docs/TESTING.md
+++ b/docs/TESTING.md
@@ -210,9 +210,9 @@ terminal client; a saved login from one signs in the other.
 
 1. `play crash` shows the ready board with a 1.00x multiplier; Space starts and
    reserves the bet.
-2. The multiplier rises smoothly with no network traffic. Cash out with C and
-   confirm the board shows the cashout multiplier, the payout and the new
-   balance.
+2. The multiplier rises smoothly from the server-clock anchor and is refreshed
+   by 10 Hz ticks. Cash out with C and confirm the board shows the cashout
+   multiplier, the payout and the new balance.
 3. On another round, press nothing. The board must switch to `CRASHED at Xx`
    by itself when the crash point is reached, and the bet must be lost.
 4. Press C just as a round crashes. Either it pays or the crashed result wins;
@@ -220,8 +220,11 @@ terminal client; a saved login from one signs in the other.
 5. Q during a live round forfeits the bet; Q when idle just leaves.
 6. Check the audit rows: one per round, `game_type = crash`, the reserved bet,
    the payout, and `crash_point`/`multiplier`/`result` in `details`.
-7. Confirm the crash point is absent from the `CRASH_START` line (it must only
-   appear once the round is over).
+7. Confirm the crash point and seed are absent from the `CRASH_START` message;
+   only `commit` and `started_at` appear. When the round ends, `seed` appears
+   and `sha256(seed) == commit`; recompute the crash point from the seed.
+8. Confirm `CRASH_BUSTED` is an `EVT`, not a `RES`, and that a second poll
+   produces no repeated settlement.
 
 ## Manual restart check
 
@@ -237,7 +240,7 @@ terminal client; a saved login from one signs in the other.
 
 1. Connect a client and server from the same release: the client connects and
    the server log shows the `HELLO` exchange.
-2. Connect a 4.x client to a 3.x server (or the reverse): the client must print
+2. Connect a 5.x client to a 4.x server (or the reverse): the client must print
    `Version mismatch: client ..., server ...` and never reach the login prompt.
 3. With a deliberately skew-built server (PATCH differs) the connection is
    accepted and, when the server's version is newer, the client prints
@@ -269,9 +272,11 @@ terminal client; a saved login from one signs in the other.
 
 ## Packaging checklist
 
-1. Set the version in `Cargo.toml` and `gui/Cargo.toml` (same MAJOR.MINOR),
-   run `cargo test --workspace`, and commit. `publish.sh` refuses a dirty tree
-   because the site links the committed git history as the GPL source.
+1. Set the version in `Cargo.toml`, `gui/Cargo.toml` and `webd/Cargo.toml`
+   (same MAJOR.MINOR), run `cargo test --workspace`, build the browser app
+   (`cd web/play && npm ci && npm run build`), and commit. `publish.sh` refuses
+   a dirty tree because the site links the committed git history as the GPL
+   source.
 2. `./scripts/publish.sh` (add `DEST=` to stage elsewhere). It builds the GUI
    with `gui-release` and the terminal clients and servers. The installers are
    stable site files and are not regenerated.
@@ -284,4 +289,33 @@ terminal client; a saved login from one signs in the other.
    menu entry. It must install the newest version even when an older app sits
    next to it, and refuse a corrupted download.
 5. Repeat on Windows for the `.ps1` installer and the Start-menu shortcut.
+6. Start `webd` against the staging server with a pinned fingerprint and open
+   `/play/` through nginx. Run the manual web checklist below.
+
+## Manual web checklist
+
+1. Open `/play/` in a fresh browser. The auth card must appear; the top bar
+   must not claim a balance until login.
+2. Register, then log in with the password. The lobby must show 1 000 Kr and
+   every game. Refresh the page; the session cookie must reattach and the
+   balance must survive (within `ZAGAN_GRACE_SECONDS`).
+3. Open the same URL in a second tab. The first tab must show "Opened in
+   another tab" and stop reconnecting; the second must continue.
+4. Slots: spin and watch the reels settle on the server result; check the
+   payout and balance. Roulette: place straight, dozen, column and outside
+   chips, right-click one back, clear, spin, and confirm the result.
+5. Blackjack: deal, hit/stand/double, then deal again; forfeiting must warn
+   and lose the reserved bet.
+6. Crash: start a round, watch the curve and ticks, cash out; on another
+   round let it bust. Confirm the reveal line shows `sha256(seed) == commit`
+   and the recomputed crash point matches.
+7. Refresh in the middle of a live crash round. The current view must return
+   with the same `commit` and a rising multiplier; the round must still settle.
+8. Close the tab mid-round and wait past the grace window. The next visit must
+   log in again, and the server must have forfeited the round.
+9. Stop the gateway. The browser must show the reconnect overlay, then recover
+   when `webd` returns. Stop it for longer than the grace window: the round is
+   forfeited and a login is required.
+10. Check the browser console: no credential is stored, the cookie is HttpOnly,
+    and the only network target is `/ws`.