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/header.php

@@ -1,5 +1,5 @@
 <header>
-    <a href="<?=htmlspecialchars(\Aternos\Mclogs\Util\URL::getBase()->toString()); ?>" class="logo">
+    <a href="<?=htmlspecialchars(\IndifferentKetchup\Iblogs\Util\URL::getBase()->toString()); ?>" class="logo">
         <svg class="logo-icon" width="41" height="42" viewBox="0 0 41 42" fill="none"
              xmlns="http://www.w3.org/2000/svg">
             <rect width="41" height="5" rx="2" fill="currentColor"/>
@@ -8,7 +8,7 @@
             <rect y="27.75" width="33" height="5" rx="2" fill="currentColor"/>
             <rect y="37" width="41" height="5" rx="2" fill="currentColor"/>
         </svg>
-        <span class="logo-text"><?= htmlspecialchars(\Aternos\Mclogs\Config\Config::getInstance()->getName()); ?></span>
+        <span class="logo-text"><?= htmlspecialchars(\IndifferentKetchup\Iblogs\Config\Config::getInstance()->getName()); ?></span>
     </a>
     <div class="tagline">
         <h1 class="tagline-main"><span class="title-verb">Paste</span> your logs.</h1>