docs(architecture): add explanation of data loading strategy for dropdowns

- Introduce pre-fetching strategy using ThrottledFetchingService
- Address limitations of Flutter DropdownButtonFormField
- Describe implementation details and user experience
- Highlight tradeoffs for initial data load vs. seamless UI

Author: fulleni

src/content/docs/web-dashboard/architecture/data-loading-strategy.mdx

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+---
+title: Data Loading Strategy
+description: An explanation of the pre-fetching strategy for dropdown data in the web dashboard.
+---
+import { Aside } from '@astrojs/starlight/components';
+
+A key architectural decision in the web dashboard is the strategy for loading data into selection fields, such as the `Country` and `Language` dropdowns found in the content creation and editing forms.
+
+### The Challenge: UI Component Limitations
+
+The dashboard uses the standard Flutter `DropdownButtonFormField` to ensure a consistent and native user experience. However, a known limitation of this widget is its lack of support for scroll detection or on-demand pagination. This makes it impossible to dynamically load more items as a user scrolls through a long list.
+
+### The Solution: Pre-Fetching with `ThrottledFetchingService`
+
+To provide a seamless user experience and work around this limitation, we've implemented a **pre-fetching strategy**.
+
+When a user navigates to a section that requires this data (like Content Management), the `ContentManagementBloc` dispatches an event to fetch the *entire* list of required items (e.g., all countries, all languages) in the background.
+
+This process is handled by the `ThrottledFetchingService`, which is designed to be efficient and respectful to the API:
+-   It fetches the first page of data to understand the total scope.
+-   It then fetches the remaining pages sequentially, with a small, built-in delay between each request to avoid overwhelming the server.
+
+### The User Experience
+
+This background fetching is designed to be as unobtrusive as possible.
+-   If a user opens a form before the data has finished loading, the relevant dropdown menu will be temporarily disabled.
+-   A helper text message, "Loading full list...", will appear below the dropdown to inform the user that the data is on its way.
+-   Once the fetch is complete, the dropdown automatically becomes active, populated with the full list of options.
+
+This approach represents a deliberate engineering tradeoff: we accept the cost of a larger initial data load in exchange for a smoother, more consistent user interface without the complexity of implementing custom dropdown components.