Add Activepieces integration for workflow automation

- Add Activepieces fork with SmoothSchedule custom piece
- Create integrations app with Activepieces service layer
- Add embed token endpoint for iframe integration
- Create Automations page with embedded workflow builder
- Add sidebar visibility fix for embed mode
- Add list inactive customers endpoint to Public API
- Include SmoothSchedule triggers: event created/updated/cancelled
- Include SmoothSchedule actions: create/update/cancel events, list resources/services/customers

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

activepieces-fork/packages/pieces/community/mailchain/src/index.ts

@@ -0,0 +1,18 @@
+import { createPiece } from '@activepieces/pieces-framework';
+import { mailchainCommon } from './lib/common/common';
+import { getAuthenticatedUser } from './lib/actions/get-authenticated-user';
+import { sendEmail } from './lib/actions/send-email';
+
+export const mailchain = createPiece({
+  displayName: 'Mailchain',
+  description:
+    'Mailchain is a simple, secure, and decentralized communications protocol that enables blockchain-based email.',
+  auth: mailchainCommon.auth,
+  minimumSupportedRelease: '0.20.0',
+  categories: [],
+  logoUrl:
+    'https://cdn.activepieces.com/pieces/mailchain.png',
+  authors: ['ahmad-swanblocks'],
+  actions: [getAuthenticatedUser, sendEmail],
+  triggers: [],
+});