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>

omsorgapp/src/main.jsx

@@ -0,0 +1,13 @@
+import React from "react";
+import { createRoot } from "react-dom/client";
+import App from "./app/app";
+import { AuthProvider } from "./app/AuthContext";
+import "./style.css";
+
+createRoot(document.getElementById("root")).render(
+  <React.StrictMode>
+    <AuthProvider>
+      <App />
+    </AuthProvider>
+  </React.StrictMode>
+);