v2: add Chat SDK channel adapters and skills for 11 platforms

Thin wrapper adapters + SKILL.md for Slack, Telegram, GitHub, Linear,
Google Chat, Teams, WhatsApp Cloud API, Resend, Matrix, Webex, iMessage.
All follow the same pattern as discord-v2.ts: readEnvFile → create*Adapter
→ createChatSdkBridge → registerChannelAdapter.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/channels/resend-v2.ts

@@ -0,0 +1,23 @@
+/**
+ * Resend (email) channel adapter (v2) — uses Chat SDK bridge.
+ * Self-registers on import.
+ */
+import { createResendAdapter } from '@resend/chat-sdk-adapter';
+
+import { readEnvFile } from '../env.js';
+import { createChatSdkBridge } from './chat-sdk-bridge.js';
+import { registerChannelAdapter } from './channel-registry.js';
+
+registerChannelAdapter('resend', {
+  factory: () => {
+    const env = readEnvFile(['RESEND_API_KEY', 'RESEND_FROM_ADDRESS', 'RESEND_FROM_NAME', 'RESEND_WEBHOOK_SECRET']);
+    if (!env.RESEND_API_KEY) return null;
+    const resendAdapter = createResendAdapter({
+      apiKey: env.RESEND_API_KEY,
+      fromAddress: env.RESEND_FROM_ADDRESS,
+      fromName: env.RESEND_FROM_NAME,
+      webhookSecret: env.RESEND_WEBHOOK_SECRET,
+    });
+    return createChatSdkBridge({ adapter: resendAdapter, concurrency: 'queue' });
+  },
+});