refactor: rename Aternos\Mclogs to IndifferentKetchup\Iblogs

Bulk substitution across all PHP files in src/, build.php, worker.php,
and web/frontend/. Updates composer.json's package name and PSR-4
autoload root accordingly. Casing matches the existing
IndifferentKetchup\Codex package's namespace convention (capital K).

Strictly a namespace rename. Aternos\Codex\* imports remain in place;
those get re-pointed in a follow-up commit when the codex Composer
dependency itself is swapped. Filename renames (docker/mclogs.ini,
web/public/css/mclogs.css), README walk-through, env-var prefix changes,
and visible-text branding land in subsequent commits.

web/frontend/parts/favicon.php

@@ -1,4 +1,4 @@
-<svg width="41" height="42" viewBox="0 0 41 42" fill="<?=htmlspecialchars(\Aternos\Mclogs\Config\Config::getInstance()->get(\Aternos\Mclogs\Config\ConfigKey::FRONTEND_COLOR_ACCENT)); ?>" xmlns="http://www.w3.org/2000/svg">
+<svg width="41" height="42" viewBox="0 0 41 42" fill="<?=htmlspecialchars(\IndifferentKetchup\Iblogs\Config\Config::getInstance()->get(\IndifferentKetchup\Iblogs\Config\ConfigKey::FRONTEND_COLOR_ACCENT)); ?>" xmlns="http://www.w3.org/2000/svg">
     <rect width="41" height="5" rx="2"/>
     <rect y="9.25" width="33" height="5" rx="2"/>
     <rect y="18.5" width="19" height="5" rx="2"/>