Reorganize into monorepo layout, move mitarbeiter-app to legacy reference

Consolidates the previously separate omsorgapp and omsorgCore repos
(each had their own nested .git with GitHub history) plus the old
root-level website/mitarbeiter-app into a single monorepo, matching
the structure already documented in the root CLAUDE.md. Also moves
the PHP employee app aside as omsorgWeb/mitarbeiter-app-legacy/ to
serve as a template for a ground-up rewrite.

Fixes .gitignore in the same pass: the config-secrets/uploads/data
patterns were unanchored (relative to repo root, not depth-agnostic),
so they silently stopped matching once the app moved under omsorgWeb/.
Patterns are now **/-prefixed and cover both mitarbeiter-app and
mitarbeiter-app-legacy, keeping DB/SMTP credentials and uploaded
employee documents out of version control.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

omsorgWeb/mitarbeiter-app-legacy/actions/logout.php

@@ -0,0 +1,11 @@
+<?php
+require_once __DIR__ . '/../lib/auth.php';
+$_SESSION = [];
+if (ini_get('session.use_cookies')) {
+    $p = session_get_cookie_params();
+    setcookie(session_name(), '', time() - 42000,
+        $p['path'], $p['domain'], $p['secure'], $p['httponly']);
+}
+session_destroy();
+header('Location: ../index.php');
+exit;