Share a turn with the world: /watch links, cards and chrome included

The share button lands on the instant replay. One click mints a slug —
persistent, unguessable, one per (room, turn) — and copies a /watch
link anyone can open: the server rebuilds exactly that turn for the
nameless SPECTATOR, public knowledge only, none of the rest of the
game visible. The page arrives with its OpenGraph card pre-baked into
the head (crawlers never run the app): the turn's title and round in
the text, and an og.png of the maze itself — cells, walls, doors, warp
mouths, homes, standees — painted server-side and PNG-encoded with
nothing but node's own zlib. The viewer page wears its chrome: the
WIZ-WAR masthead linking home, the turn's title, the reel opening
straight into the turn-owner's eyes with a "watch it again" loop, and
a footer that says what this table is and deals the visitor in.

The share page loads as its own entry so a shared link never drags the
full app's socket appetite along; the reel's modal scrim learns to
stand in a page instead of over one.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/net.svelte.ts

@@ -321,6 +321,9 @@ class Net {
   private turnCounter = -1;
   /** The turn that already carries an instant-replay eye (one per turn). */
   private eyeTurn = -1;
+  /** The turn whose moment reel is open (share links point at it). */
+  private momentTurn: number | null = null;
+  private shareResolve: ((url: string) => void) | null = null;
   private seen: Record<string, number> = loadSeen();
   /** Room whose live stream this connection has already shown once: states
    * after the first mark themselves seen while the tab is visible. */
@@ -423,6 +426,10 @@ class Net {
         case "moment":
           this.moment = msg.steps;
           break;
+        case "share":
+          this.shareResolve?.(`${location.origin}/watch/${msg.id}`);
+          this.shareResolve = null;
+          break;
         case "events": {
           let talk = 0;
           if (!msg.replayed) this.onFx?.(msg.events as GameEvent[]);
@@ -688,9 +695,25 @@ class Net {
 
   /** Summon one turn's reel by its chronicle turn number. */
   requestMoment(turn: number): void {
+    this.momentTurn = turn;
     this.send({ type: "moment", turn });
   }
 
+  /** Mint a public link to the open moment's turn. */
+  requestShare(): Promise<string> {
+    return new Promise((resolve, reject) => {
+      if (this.momentTurn === null) return reject(new Error("no turn open"));
+      this.shareResolve = resolve;
+      this.send({ type: "share", turn: this.momentTurn });
+      setTimeout(() => {
+        if (this.shareResolve === resolve) {
+          this.shareResolve = null;
+          reject(new Error("share timed out"));
+        }
+      }, 10_000);
+    });
+  }
+
   closeMoment(): void {
     this.moment = null;
   }