feat: Add Ghost CMS integration

[siva-sub]

This is an update/supersede of PR #1142 with comprehensive Ghost CMS integration fixes.

Fixes #1142 - Adds native Ghost CMS integration with scheduling, theme management, newsletters, and tiers support.

Original PR #1142 Summary

• Ghost Admin API integration using JWT authentication (HS256)
• Custom fields for Ghost site URL and Admin API key configuration
• Frontend settings form with title, slug, status, feature image, tags
• Image upload support for feature images
• HTML editor mode for rich content

Additional Features in This PR

• Native scheduling, update, delete via Ghost Admin API
• Theme upload, activation, and settings management
• Newsletters and tiers support with proper DTOs

Bug Fixes (Critical)

• Fix Sentry issue: Added updated_at field fetching to prevent 409 UPDATE_COLLISION errors
• The Ghost Admin API requires updated_at timestamp for optimistic concurrency control
• Both update() and changeStatus() now fetch current post before editing to get correct updated_at
• Fix null check in changeDate() to prevent NPE when post doesn't exist

Code Quality

• All files have trailing newlines for lint compliance
• Proper TypeScript types and DTOs

Testing

• Tested with local Postiz instance and self-hosted Ghost
• Post creation, update, and status changes work correctly
• Image uploads verified

---

Supersedes: #1142

[vercel]

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[sentry]

Bug: The update() and changeStatus() methods are missing the required updated_at field in Ghost API calls, which will cause all post updates to fail.
_{Severity: CRITICAL}

Suggested Fix

Before calling api.posts.edit() in both the update() and changeStatus() methods, first fetch the current post using api.posts.read({ id: ghostPostId }). Then, include the updated_at value from the fetched post in the updateData object sent to the API.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: libraries/nestjs-libraries/src/integrations/social/ghost.provider.ts#L973-L977

Potential issue: The `update()` and `changeStatus()` methods in the Ghost provider fail
to include the `updated_at` field in the payload for `api.posts.edit()` calls. The Ghost
Admin API requires this field for optimistic concurrency control to prevent write
conflicts. Its absence will cause the API to return a 409 `UPDATE_COLLISION` error for
every update attempt, effectively breaking all post editing and status change
functionality.

[siva-sub]

✅ Fixes Applied

1. updated_at for Optimistic Concurrency (CRITICAL)

Fixed in commit ff75abe.

The update() and changeStatus() methods now fetch the current post using api.posts.read({ id: ghostPostId }) before calling api.posts.edit(), and include the updated_at timestamp from the fetched post.

// update() method - lines 974-981
const currentPost = await api.posts.read({ id: ghostPostId }, { include: 'tags,authors' });
if (!currentPost) {
  throw new Error('Post not found');
}
updateData.updated_at = currentPost.updated_at;

This satisfies Ghost Admin API's optimistic concurrency control requirement and prevents 409 UPDATE_COLLISION errors.

2. email_only validator (HIGH)

This appears to already be correct in the codebase - ghost.dto.ts line 129 shows @IsBoolean() decorator on the email_only?: boolean field. The Sentry bot comment may have been based on an outdated code snapshot.