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.

Hardware/.gitignore

@@ -0,0 +1,54 @@
+# KiCad
+# Ignore backup files
+*.bak
+*.bck
+*~
+#*
+.#*
+*.kicad_pcb-bak
+*.kicad_pro.bak
+*.kicad_sch.bak
+
+# Ignore automatically generated files
+*.erc
+*.net
+*-cache.lib
+*-rescue.lib
+*.dcm
+*.lib
+*.mod
+*.cmp
+*.gbr
+*.drl
+*.pos
+*.rpt
+*.log
+*.zip
+*.pdf
+*.svg
+*.png
+*.json
+*.html
+*.xml
+*.csv
+*.txt
+*.bom
+*.kicad_wks
+*.kicad_dru
+*.kicad_sym
+*.kicad_mod
+*.fpc
+*.kicad_prl
+
+# Project local settings files and backups
+*.kicad_prl
+
+# macOS specific files
+.DS_Store
+._*
+
+# Windows specific files
+Thumbs.db
+
+# Editor/OS fluff
+*.swp