docs: Enhance documentation for concept

docs/src/product-direction/concepts/concepts.md

@@ -1,3 +1,9 @@
 ---
 icon: book
----
+---
+
+# Concepts
+
+Here you can find concepts of upcoming features and ideas that are being discussed in the community. 
+These concepts are not yet implemented, but they provide a glimpse into the future direction of the project. 
+We welcome feedback and suggestions on these concepts, so please feel free to share your thoughts.

docs/src/product-direction/concepts/fancynpcs/fancynpcs.md

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-redirect: custom-models.md
+redirect: action-scripting
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 # FancyNpcs

docs/src/product-direction/concepts/tools/lightweight-minecraft-client-sdk.md

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 # Lightweight Minecraft Client SDK
 
-TODO
+## Problem
+
+We need a lightweight Minecraft Client which can easily run in GitHub Actions or other CI systems to run e2e tests.
+
+## Solution
+
+The solution is to create a lightweight Minecraft Client SDK that can be used in GitHub Actions or other CI systems to run e2e tests. 
+The SDK should be able to have the basic functionality of a Minecraft Client:
+- Connect to a Minecraft server
+- Run commands
+- Interact with the world and entities
+- Send and receive packets
+
+The SDK should provide a simple API that can be used to interact with the Minecraft server.
+
+The SDK should have an easy way to get notified of any incoming packets from the server, to test our packet library.

docs/src/product-direction/concepts/tools/modrinth-sdk.md

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-# Modrinth SDK
-
-TODO

docs/src/product-direction/concepts/tools/plugin-testing-framework.md

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 # Plugin Testing Framework
 
-TODO
+The Plugin Testing Framework is a tool that allows developers to test their plugins in a controlled environment. 
+It provides a set of tools and libraries that make it easy to create and run tests for plugins, ensuring that they work as expected and do not introduce any bugs or issues.
+
+**Workflow:**
+1. Start a Minecraft server with the plugin installed.
+2. Let a [lightweight minecraft client](lightweight-minecraft-client-sdk.md) connect to the server.
+3. Run tests
+4. Assert results (e.g., if the correct packets were sent)
+5. Stop the server and the client
+
+This process can be automated using GitHub Actions or other CI systems, allowing developers to run tests automatically whenever they make changes to their plugins.