fix: sync $_REQUEST after modifying $_GET in SiteURIFactory

[jalexiscv]

Description

Fixes #9872 - getVar() behaves inconsistently with GET parameters

Problem

When SiteURIFactory modifies $_GET via setGetArray() during request URI parsing, it does not update $_REQUEST. Since IncomingRequest::getVar() reads from $_REQUEST, validation methods like $validator->withRequest() receive stale data.

Solution

1. Add Superglobals::syncRequest() method that rebuilds $_REQUEST from $_GET, $_POST, and $_COOKIE respecting PHP request_order
2. Call syncRequest() in SiteURIFactory after each setGetArray() call

Changes

• system/Superglobals.php: Add syncRequest() method
• system/HTTP/SiteURIFactory.php: Call syncRequest() after setGetArray()

Testing

• All existing tests pass (no regressions)
• Manual verification confirms $_REQUEST syncs correctly

Ref: #9872
Closes #9872

[mergeable]

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[neznaika0]

This has already been discussed. The $_request does not change after the request. The right solution would be to abandon getVar() as deprecated.