Fix for Duplicate Entry SQL Error on 'pages' Table

[thecrazybob]

This PR addresses a SQLSTATE[23000] integrity constraint violation error encountered when inserting a new page with a non-unique slug into the pages table. The error was caused by the pages_slug_unique constraint on the slug column.

Problem:
The application threw an exception for a duplicate entry for the key pages.pages_slug_unique when attempting to insert a new page with the same slug as an existing page, but with a different parent.

Solution:
The unique index on the slug column has been removed, and a new compound unique index has been introduced on the combination of slug and parent_id columns. This allows the same slug to be used as long as it has a different parent, thus ensuring unique URLs for different page hierarchies while avoiding the integrity constraint violation.

[what-the-diff]

PR Summary

• Modification to slug field in create_pages_table.php.stub
  The blueprint of the website's pages underwent a slight alteration where the website addresses (termed 'slugs') are no longer required to be unique.

• Introduction of parent_id field in create_pages_table.php.stub
  A new element known as 'parent_id' has been introduced, which is combined with the 'slug' to create a unique key. This translates to better organization of the pages on the website as they're now parented and structured more effectively.

• Updated Migration matching the above changes
  The database changes made in the create_pages_table.php.stub file have been synchronized with the website's database system (a process known as migration) to ensure that these improvements are reflected site-wide.

[Z3d0X]

Hi thanks for noticing this bug. Please create new migration file to fix this. Avoid editing the existing migration file

• Create a new migration file to fix unique index

[Z3d0X]

#134
Please submit a new PR fixing this