style(tracegrind): apply clang-format and add pre-commit hook

Add .pre-commit-config.yaml with clang-format scoped to tracegrind/ only.
Reformat all tracegrind source files to match the repo's .clang-format style.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: art049

.pre-commit-config.yaml

@@ -0,0 +1,7 @@
+repos:
+  - repo: https://github.com/pre-commit/mirrors-clang-format
+    rev: v14.0.6
+    hooks:
+      - id: clang-format
+        files: ^tracegrind/
+        types_or: [c, c++]