feat: Add contribution guidelines and hardware config

- Adds CONTRIBUTING.md and a German translation to establish commit message conventions.

- Creates a Hardware/ directory with a .gitignore for KiCad projects.

- Refactors and improves the power supply documentation.

CONTRIBUTING.md

@@ -0,0 +1,42 @@
+# Contribution Guidelines
+
+To ensure a consistent and readable git history, this project adheres to the [Conventional Commits](https://www.conventionalcommits.org/) specification.
+
+## Commit Message Format
+
+Each commit message consists of a **header**, a **body**, and a **footer**.
+
+```
+<type>[optional scope]: <description>
+
+[optional body]
+
+[optional footer]
+```
+
+### Type
+
+The type must be one of the following:
+
+*   **feat**: A new feature for the user.
+*   **fix**: A bug fix for the user.
+*   **docs**: Changes to the documentation.
+*   **style**: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc).
+*   **refactor**: A code change that neither fixes a bug nor adds a feature.
+*   **perf**: A code change that improves performance.
+*   **test**: Adding missing tests or correcting existing tests.
+*   **chore**: Changes to the build process or auxiliary tools and libraries such as documentation generation.
+*   **build**: Changes that affect the build system or external dependencies.
+*   **ci**: Changes to our CI configuration files and scripts.
+
+### Description
+
+The description is a short summary of the code changes. Use the imperative, present tense: "change" not "changed" nor "changes".
+
+### Breaking Changes
+
+A commit that has a footer beginning with `BREAKING CHANGE:` introduces a breaking API change. A BREAKING CHANGE can be part of any type of commit.
+
+---
+
+*This document provides a summary. For more details, please refer to the [official Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/).*