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/assets/team.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 900 620"><rect width="900" height="620" rx="36" fill="#11111f"/><circle cx="170" cy="130" r="95" fill="#68d2df" opacity=".45"/><circle cx="760" cy="500" r="120" fill="#68d2df" opacity=".18"/><g fill="#fff"><circle cx="295" cy="250" r="58"/><circle cx="450" cy="225" r="70"/><circle cx="610" cy="250" r="58"/></g><g fill="#68d2df"><path d="M185 465c35-115 185-115 220 0z"/><path d="M305 490c42-145 248-145 290 0z"/><path d="M500 465c35-115 185-115 220 0z"/></g><text x="90" y="95" font-family="Arial" font-size="34" font-weight="800" fill="#fff">Menschen im Mittelpunkt</text></svg>