API/MCP returns raw translation key when editing a finalized post

[paulocastellano]

Bug

When a client tries to edit/update a post that is already finalized (published, publishing, partially_published, or failed), the API and MCP return a broken error message: the raw translation key instead of the human-readable string.

Observed

{ "message": "posts.cannot_edit_finalized" }

Expected (English)

{ "message": "This post has already been processed and cannot be re-published. Duplicate it to try again." }

Root cause

App\Support\PostStatusRules::editBlockedMessage() uses:

private const EDIT_BLOCKED_MESSAGE_KEY = 'posts.cannot_edit_finalized';

But the string only exists under posts.flash.cannot_edit_finalized in lang/*/posts.php.

• Web UI already uses the correct key: __('posts.flash.cannot_edit_finalized') (e.g. PostController).
• API (Api\PostController) and MCP (UpdatePostTool, PublishPostTool) go through PostStatusRules::editBlockedMessage() and hit the wrong key.

Verified locally:

Call	Result
__('posts.cannot_edit_finalized')	posts.cannot_edit_finalized (missing)
__('posts.flash.cannot_edit_finalized')	Correct English copy
PostStatusRules::editBlockedMessage()	Raw key

Suggested fix

Either:

1. Change EDIT_BLOCKED_MESSAGE_KEY to posts.flash.cannot_edit_finalized, or
2. Add a top-level posts.cannot_edit_finalized key (and keep flash as an alias), so API/MCP and flash stay in sync.

Also update any MCP/API tests that assert __('posts.cannot_edit_finalized') so they assert the resolved human string (or the corrected key).

Affected surfaces

• PUT /api/posts/{post} when the post is finalized
• MCP update-post-tool / publish-post-tool when the post is finalized