Integration of eMeal - Menüplanung into the eCamp3 Project

I'm one of the maintainers of the project [eMeal - Menüplanung](https://github.com/wp99cp/eMeal_menuplanung). We are currently planning and conceptualize version 2 of our project. During that initial planning phase, the idea came up that we would like to provide some integration of our tool into eCamp3. As discussed in https://github.com/ecamp/ecamp3/issues/5169#issuecomment-2107175552, such coupling should be as loose as possible while providing a consistent experience to the end user. Thus, we are **not** planning to integrate eMeal into eCamp3 directly but rather to provide some integration based on cross-references and API calls.

We are thinking the following integrations would be beneficial:

- **Cross-Referencing between the tools:**
In eMeal (or eCamp), one can reference any existing camp in eCamp (or eMeal); the counterpart must confirm this reference. A link then allows for fast navigation between the two tools.

- **Synchronizing Schedule Entries and Activity-Meta-Data to eMeal**
The camp leader plans and places activity blocks for the type of meal inside the week overview. He may associate additional meta-data with every meal entry, such as a title, location and short description. Those meta-data are then displayed within eMeal. Data sent to eMeal could look as follows:
```
type: Mittagessen
time: 2024-07-01, 12.00
description: "Grosses Festessen nach gewonnener Schlacht"
location: "Im Lagerhaus"
```

- **Synchronizing Meal-Title back to eCamp3**
After the kitchen team creates a complementary meal inside eMeal, the data is synchronized back to eCamp3, i.e. the meal title (including some higher-level recipe info) is displayed inside eCamp3.
```
type: Mittagessen
time: 2024-07-01, 12.00
meal-title: "Spaghetti-Plaus mit verschiedenen Saucen"
```

- **Optional: Synchronizing of Access Roles:**
Once linked, all managers within a camp in eCamp3 automatically get view access to the corresponding camp within eMeal. Thus, the camp leader can always view what the kitchen team is planning.

- **Optional: Synchronizing of Participants Counts:**
As far as I know, linking a camp within eCamp3 with a corresponding entry within MiData / CeviDB is not yet possible. If and once such a feature is implemented, sharing the participant count with eMeal would be beneficial. Usually, only the camp leader knows the exact participant count, whereas the kitchen team relies on him to report those numbers.

What does the eCamp3 community think of those plans? Which of the above interactions are realistic/valuable? Are there any essential things to consider? Are there any other requirements?

_Disclaimer: The ideas discussed in this issue are very high-level; I know that many implementation details need in-depth discussions. We are currently pretty flexible as we are still planning our architecture._