feat(protocol2): guild and town-governor world-state streams (Part B ph.1)

Adds the first Part B streams from docs/PROTOCOL_2.md: guild rosters and
town governors ("mayors"), both outbound diff-board sweeps mirroring the
existing champ board.

Overlay:
- BridgeSocial (new): guild sweep+diff over BaseGuild.List -> guild.update /
  guild.remove (full-state upsert; disband detected via Disbanded), plus a
  real-time guild.join from EventSink.JoinGuild. (EventSink.CreateGuild is only
  the load-time factory, so creation is derived sidecar-side from a first-seen
  id, as champs do.)
- BridgeGovernance (new): city sweep over CityLoyaltySystem.Cities -> city.update
  (governor / governor-elect / election phase), gated on CityLoyaltySystem.Enabled.
- BridgeJson.Actor: shared serial/name/acct/webId/player writer used by both.
- BridgeConfig: GuildSweepSeconds (60s), CitySweepSeconds (300s).
- BridgeBoot: both wired into [bridge reload|sweepnow|status.

Sidecar:
- store: guilds + governors board tables with upsert/delete/all.
- main: route guild.update/remove and city.update into the boards.
- web: GET /guilds, GET /governors served from the store (snapshot-companion
  rule, so a fresh page or a restarted sidecar hydrates without the shard).

Docs: INTEGRATION.md event catalog (guild.*, city.update) + board endpoints;
PROTOCOL_2.md Part B phase 1 marked built.

Verified: sidecar cargo check clean; overlay compiles in the full ServUO
Scripts tree (0 errors, 0 warnings). Live end-to-end run still pending.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

overlay/Scripts/Custom/Bridge/BridgeJson.cs

@@ -76,6 +76,46 @@ namespace Server.Custom.Bridge
             return sb;
         }
 
+        /// <summary>
+        ///     Writes a nested actor object: serial, name, account (when there is one), the linked
+        ///     webId (when the account is linked), and the player flag. A `null` mobile writes null.
+        ///     The richer counterpart to BridgeEvents' internal writer, used by the Part B streams so a
+        ///     guild leader / joiner / governor can be attributed to a site user without a lookup.
+        /// </summary>
+        public static StringBuilder Actor(this StringBuilder sb, string name, Mobile m)
+        {
+            sb.Append(",\"").Append(name).Append("\":");
+
+            if (m == null)
+            {
+                sb.Append("null");
+                return sb;
+            }
+
+            sb.Append("{\"serial\":\"0x").Append(m.Serial.Value.ToString("X")).Append('"');
+
+            sb.Append(",\"name\":");
+            Escape(sb, m.Name ?? "");
+
+            var acct = m.Account as Accounting.Account;
+            if (acct != null)
+            {
+                sb.Append(",\"acct\":");
+                Escape(sb, acct.Username);
+
+                var webId = BridgeAccountLink.WebIdFor(acct);
+                if (webId != null)
+                {
+                    sb.Append(",\"webId\":");
+                    Escape(sb, webId);
+                }
+            }
+
+            sb.Append(",\"player\":").Append(m.Player ? "true" : "false");
+            sb.Append('}');
+            return sb;
+        }
+
         /// <summary>Closes the object. The trailing newline is the frame delimiter.</summary>
         public static string End(this StringBuilder sb)
         {