Remove duplicate TestCase (dedup + composer autoload)

[jbagsik]

Context

SonarQube flagged duplicated lines on the moox/verapdf branch (mooxphp/moox feature/add-verapdf-package). The package ships two identical TestCase files — src/Tests/TestCase.php and tests/TestCase.php — both declaring the same class Moox\VeraPdf\Tests\TestCase (they only coexist via an in-file autoloader shim). This is the 96% / ~72-line duplication hit and a genuine copy-paste defect.

What to build

The package has exactly one Moox\VeraPdf\Tests\TestCase, resolved through composer autoloading, with no duplicate file and no runtime autoloader shim.

Acceptance criteria

• Only one TestCase file remains (keep the canonical location per package convention; the redundant copy is deleted).
• composer.json autoload-dev maps Moox\VeraPdf\Tests\ to the kept location; the in-file PSR-4 autoloader shim is removed.
• Pest.php still resolves TestCase; the full package suite runs green.
• SonarQube no longer reports duplication for the removed file.

Blocked by

None — can start immediately.

[jbagsik]

Additional acceptance criteria — Codacy findings on the TestCase file (fold in here):

• The kept TestCase file contains a single class in its own file (Codacy: "each class must be in a file by itself") — resolve the conditional double-class declaration (Orchestra vs ApplicationTestCase) so only one class is declared per file.
• The file declares symbols with no side effects (Codacy: side-effect + symbol in one file) — removing the in-file autoloader shim already covers this; confirm no other top-level side effects remain.