Remove unused Generator injection from GenerateAltTextAction

[robocopklaus]

Summary

GenerateAltTextAction injects a Generator instance via constructor, but it is never used. The actual generation is handled by new GenerateAltText() which dispatches a job. The unnecessary constructor override also risks breaking compatibility if Statamic's base Action class adds a constructor.

Problem

// GenerateAltTextAction.php:18-23
public function __construct(
    protected Generator $generator,
) {
    //
}

The $generator property is never referenced in run() or any other method.

Suggested Fix

Remove the $generator property and constructor entirely.

References

• File: src/Actions/GenerateAltTextAction.php:18-23
• Consolidated review finding: V9