Feature/guidelines design

[NickBevers]

No description provided.

[sebastiandedeyne]

Content changes summary:

Split "Laravel & PHP" into two separate pages

The single laravel-php.md page has been split into:

• php.md (weight 1) — PHP-specific guidelines
• laravel.md (weight 2) — Laravel-specific guidelines

New content in php.md

final and readonly stance expanded — The old single-line statement about not using final has been expanded to cover readonly as well:

• final: Same reasoning as before (not much benefit, team doesn't rely on inheritance)
• readonly: Not worth the extra keyword; context (e.g. DTOs, resources) already makes read-only intent clear

New "Class constants" section — Class constants should follow PascalCase (same rule as enums), e.g. Session::SessionTokenHeader.

[jimirobaer]

Added small styling tweaks (font size, responsive tweak) and fixed two SVGs (strokes not being outlined made they appear look weird). Other than that, lgtm!