docs: Dokumentation nach Projektstandard, MIT-Lizenz

- README knapp: Zweck, Schnellstart, Stand, Abschnitt "Documentation", Lizenz
- FUNKTIONSWEISE.md neu: Aufbau, Datenfluss (Mermaid), Entscheidungsregel,
  Normalform, elastischer Bildvergleich, Quellen, Sicherheit, Messungen,
  Designentscheidungen, Grenzen
- BEDIENUNGSANLEITUNG gegliedert: Installation, Modellserver, Benutzung,
  Konfiguration (Umgebungsvariablen, workspace.json), Betrieb, Werkzeuge,
  Fehlersuche mit echten Meldungen und Rückgabecodes
- CHANGELOG im Format Keep a Changelog mit "Beim Update zu tun"
- LICENSE (MIT)
- cli.py: Hilfetexte beschreiben die Regel p2t und z-ai/glm-4.6v statt des
  Pixelvergleichs und gemini-2.5-flash
- requirements.txt: requests ergänzt

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Dieter Schlüter
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.