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/upload-dokument.php

@@ -0,0 +1,42 @@
+<?php
+require_once __DIR__ . '/../lib/auth.php';
+require_once __DIR__ . '/../lib/upload.php';
+require_login();
+
+if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+    header('Location: ../pages/dokumentenarchiv.php');
+    exit;
+}
+
+$back = '../pages/dokumentenarchiv.php';
+
+$allowed_kategorien = ['Fortbildungsnachweis', 'Zeugnis', 'Bescheinigung', 'Sonstiges'];
+$kategorie   = trim($_POST['kategorie']   ?? '');
+$beschreibung = trim($_POST['beschreibung'] ?? '');
+
+if (!in_array($kategorie, $allowed_kategorien, true)) {
+    redirect_error($back, 'Bitte eine Kategorie auswählen.');
+}
+
+$filesize = $_FILES['datei']['size'] ?? 0;
+$up = handle_upload($_FILES['datei'] ?? [], [
+    'allowed' => UPLOAD_TYPES_DOCS,
+    'dir'     => dirname(__DIR__) . '/uploads/',
+    'prefix'  => 'dokument',
+]);
+if (!$up['ok']) {
+    redirect_error($back, $up['error']);
+}
+
+$safe_name     = $up['filename'];
+$original_name = $up['original_name'];
+
+$user_id  = current_user()['id'];
+$now      = date('c');
+
+db()->prepare(
+    'INSERT INTO dokumente (user_id, kategorie, beschreibung, filename, original_name, filesize, created_at)
+     VALUES (?, ?, ?, ?, ?, ?, ?)'
+)->execute([$user_id, $kategorie, $beschreibung, $safe_name, $original_name, $filesize, $now]);
+
+redirect_ok($back, 'ok');