Migrate documentation to Mintlify and configure 301 redirects (#15502)

## Summary
Completes the migration of all documentation from twenty-website to a
new Mintlify-powered documentation site at docs.twenty.com.

## Changes Made

### New Package: `twenty-docs`
- ✅ Created new Mintlify documentation package
- ✅ Migrated 95 content pages (user-guide, developers, twenty-ui)
- ✅ Migrated 81 images
- ✅ Converted all custom components to Mintlify native components
- ✅ Configured navigation with 2 tabs and 94 pages
- ✅ Added Helper AI Agent with searchArticles tool for docs search

### Updated: `twenty-website`
- ✅ Added 11 redirect rules (301 permanent) in next.config.js
- ✅ Removed all documentation content (111 files)
- ✅ Removed documentation routes (user-guide, developers, twenty-ui)
- ✅ Removed documentation components (9 files)
- ✅ Updated keystatic.config.ts
- ✅ Preserved all marketing/release pages

### Updated: Core Files
- ✅ Updated README.md - docs links point to docs.twenty.com
- ✅ Updated CONTRIBUTING.md - code quality link updated
- ✅ Updated SupportDropdown.tsx - user guide link updated
- ✅ Updated Footer.tsx - user guide link updated

packages/twenty-docs/user-guide/integrations-api/api-webhooks.mdx

@@ -64,7 +64,7 @@ Since your API key gives access to sensitive information, you shouldn't share it
 
 Webhooks allow for immediate updates to your specified URL about changes or events related to your customer data.
 
-For example, when an Opportunity moves to "Closed Won", a webhook can automatically trigger invoice creation in your accounting system. Note that this type of automation can also be achieved using Twenty's in-app [Workflows feature](/user-guide/section/workflows/getting-started-workflows), which offers triggers based on field updates for internal automation.
+For example, when an Opportunity moves to "Closed Won", a webhook can automatically trigger invoice creation in your accounting system. Note that this type of automation can also be achieved using Twenty's in-app [Workflows feature](/user-guide/workflows/getting-started-workflows), which offers triggers based on field updates for internal automation.
 
 Webhooks are ideal for integrating with external systems, while Workflows support both internal automation and external tool connections via webhook triggers, code nodes, and HTTP nodes.
 

packages/twenty-docs/user-guide/integrations-api/apis-overview.mdx

@@ -112,7 +112,7 @@ Your documentation is unique to your workspace because it reflects your custom o
 
 ## Next Steps
 
-- **[API & Webhooks Setup](/user-guide/section/integrations-api/api-webhooks)**: Learn how to create API keys and webhooks
+- **[API & Webhooks Setup](/user-guide/integrations-api/api-webhooks)**: Learn how to create API keys and webhooks
 - **Custom Documentation**: Access your personalized API docs via Settings → API & Webhooks
 
 

packages/twenty-docs/user-guide/integrations-api/integrations.mdx

@@ -15,7 +15,7 @@ Twenty currently offers native integration with:
 - **Email & Calendar**: Connect Gmail, Outlook, or SMTP/CalDAV providers
 - **API Access**: Use our REST and GraphQL APIs to build custom integrations
 
-For email and calendar setup, visit [Email & Calendar Setup](/user-guide/section/settings/email-calendar-setup).
+For email and calendar setup, visit [Email & Calendar Setup](/user-guide/settings/email-calendar-setup).
 
 ### Workflows (Recommended)
 The primary way to connect Twenty to other tools is through our in-app **Workflows** feature:
@@ -24,7 +24,7 @@ The primary way to connect Twenty to other tools is through our in-app **Workflo
 - **Webhook Triggers**: Receive data from external systems
 - **Field Update Triggers**: Automate actions based on CRM changes
 
-Learn more in our [Workflows section](/user-guide/section/workflows/getting-started-workflows).
+Learn more in our [Workflows section](/user-guide/workflows/getting-started-workflows).
 
 ### Zapier Integration (Legacy)
 We maintain a Zapier integration for users who prefer no-code automation: