feat(msteams): add MS Teams provider skeleton

- Add Microsoft 365 Agents SDK packages (@microsoft/agents-hosting,
  @microsoft/agents-hosting-express, @microsoft/agents-hosting-extensions-teams)
- Add MSTeamsConfig type and zod schema
- Create src/msteams/ provider with monitor, token, send, probe
- Wire provider into gateway (server-providers.ts, server.ts)
- Add msteams to all provider type unions (hooks, queue, cron, etc.)
- Update implementation guide with new SDK and progress

src/gateway/server.ts

@@ -183,6 +183,7 @@ const logDiscord = logProviders.child("discord");
 const logSlack = logProviders.child("slack");
 const logSignal = logProviders.child("signal");
 const logIMessage = logProviders.child("imessage");
+const logMSTeams = logProviders.child("msteams");
 const canvasRuntime = runtimeForLogger(logCanvas);
 const whatsappRuntimeEnv = runtimeForLogger(logWhatsApp);
 const telegramRuntimeEnv = runtimeForLogger(logTelegram);
@@ -190,6 +191,7 @@ const discordRuntimeEnv = runtimeForLogger(logDiscord);
 const slackRuntimeEnv = runtimeForLogger(logSlack);
 const signalRuntimeEnv = runtimeForLogger(logSignal);
 const imessageRuntimeEnv = runtimeForLogger(logIMessage);
+const msteamsRuntimeEnv = runtimeForLogger(logMSTeams);
 
 type GatewayModelChoice = ModelCatalogEntry;
 
@@ -501,7 +503,8 @@ export async function startGatewayServer(
       | "discord"
       | "slack"
       | "signal"
-      | "imessage";
+      | "imessage"
+      | "msteams";
     to?: string;
     model?: string;
     thinking?: string;
@@ -756,12 +759,14 @@ export async function startGatewayServer(
     logSlack,
     logSignal,
     logIMessage,
+    logMSTeams,
     whatsappRuntimeEnv,
     telegramRuntimeEnv,
     discordRuntimeEnv,
     slackRuntimeEnv,
     signalRuntimeEnv,
     imessageRuntimeEnv,
+    msteamsRuntimeEnv,
   });
   const {
     getRuntimeSnapshot,
@@ -772,12 +777,14 @@ export async function startGatewayServer(
     startSlackProvider,
     startSignalProvider,
     startIMessageProvider,
+    startMSTeamsProvider,
     stopWhatsAppProvider,
     stopTelegramProvider,
     stopDiscordProvider,
     stopSlackProvider,
     stopSignalProvider,
     stopIMessageProvider,
+    stopMSTeamsProvider,
     markWhatsAppLoggedOut,
   } = providerManager;