Replace MODX_* system constants with EVO_*

[Seiger]

Description

Currently, across the Evolution CMS codebase there are still usages of legacy system constants prefixed with MODX_ (e.g. MODX_BASE_PATH, MODX_SITE_URL, etc.).

Since Evolution CMS has moved away from MODX branding, these constants are misleading and can cause confusion for developers, especially in new projects and documentation.

Problem

• Legacy constants like MODX_* are still used internally
• They do not reflect the current identity of Evolution CMS
• This may lead to:
  • confusion for new developers
  • inconsistency in codebase
  • misperception of the system as MODX-dependent

Proposed solution

1. Replace all MODX_* constants with corresponding EVO_* equivalents:

• MODX_BASE_PATH → EVO_BASE_PATH
• MODX_SITE_URL → EVO_SITE_URL
• etc.

2. Introduce a backward compatibility layer:

defined('MODX_BASE_PATH') || define('MODX_BASE_PATH', EVO_BASE_PATH);

3. Update:

• core codebase
• documentation
• examples
• templates

Reference

A full list of currently defined system constants can be found in:

core/includes/define.inc.php

Benefits

• Clear separation from MODX legacy
• Cleaner and more consistent naming
• Better developer experience
• Easier onboarding for new users

Notes

• This change should be done carefully to avoid breaking existing projects
• Backward compatibility must be preserved for at least one major version

Scope

• Core (/core)
• Manager
• Installer
• Default templates/snippets
• Documentation

Additional context

This is part of ongoing efforts to modernize Evolution CMS and align naming conventions with the current ecosystem.

[middleDuckAi]

A first bounded slice for this work is ready.

PR: #2241

What is included in this slice:

• EVO_* becomes canonical in the touched bootstrap/runtime entrypoints
• missing MODX_* constants are backfilled from resolved EVO_* values for backward compatibility
• installer and manager runtime entrypoints touched by this slice stop defining MODX_API_MODE directly
• a fresh-process compatibility test now covers EVO_* -> MODX_* aliasing and legacy MODX_* -> EVO_* fallback

Validation:

• ./vendor/bin/pest tests/Unit/DefineConstantsCompatibilityTest.php tests/Feature/ModifiersTest.php
• php -l on the touched bootstrap, installer, and manager entrypoint files

This does not finish the full repo-wide rename yet; it opens the migration with the bootstrap/runtime layer first.

[middleDuckAi]

A second bounded slice for this migration is ready in PR #2244.

What is included in this slice:

• core manager path/url helpers now use canonical EVO_* constants
• manager frame and tree views emit EVO_* URLs first
• compatibility aliases stay in place where manager frontend runtime still expects MODX_*
• targeted regression coverage now checks manager path/url helper usage

Validation:

• ./vendor/bin/phpunit tests/Unit/ManagerPathConstantUsageTest.php
• ./vendor/bin/pest tests/Feature/ModifiersTest.php
• php -l on touched files
• local runtime smoke check on the task branch

This is still part of the broader #2238 migration, so the issue should remain Status/In-progress until the remaining slices land.