Improve documentation structure and content

[dgaida]

This PR improves the PyADM1ODE documentation by:

1. Restructuring the homepages (DE/EN) to be more concise landing pages.
2. Moving detailed content (Architecture, Components, Substrates, etc.) to dedicated sub-pages in the manual.
3. Translating all English example pages into German.
4. Adding two Jupyter notebooks for Google Colab to allow users to run simulations in the browser.
5. Organizing the MkDocs navigation with top-level entries for Handbuch (Manual), Beispiele (Examples), and Entwicklung (Development).
6. Adding "Open in Colab" badges to relevant documentation pages.

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PR created automatically by Jules for task 3660101932611991235 started by @dgaida

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