feat: add pre-commit and initial justfile

.pre-commit-config.yaml

@@ -0,0 +1,18 @@
+exclude: '^(qmk_upstream/|qmk_framework/|\.build/)'
+
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-merge-conflict
+      - id: check-added-large-files
+      - id: check-yaml
+      - id: check-json
+
+  - repo: https://github.com/pre-commit/mirrors-clang-format
+    rev: v18.1.8
+    hooks:
+      - id: clang-format
+        types_or: [c, c++]