fix: add distro agnostic shebang and clang-format check to clang-format-fix (#840)

## Summary

**What is the goal of this PR?** (e.g., Implements the new feature for
file uploading.)

Minor development tooling fix for nonstandard environments (NixOS,
FreeBSD, Guix, etc.)

**What changes are included?**

- environment relative shebang in `clang-format-fix`
- clang-format check in `clang-format-fix`
---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**NO**_

bin/clang-format-fix

@@ -1,10 +1,18 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+# Check if clang-format is availible
+command -v clang-format >/dev/null 2>&1 || {
+    printf "'clang-format' not found in current environment\n"
+    printf "install 'clang', 'clang-tools', or 'clang-format' depending on your distro/os and tooling requirements\n"
+    exit 1
+}
 
 GIT_LS_FILES_FLAGS=""
 if [[ "$1" == "-g" ]]; then
   GIT_LS_FILES_FLAGS="--modified"
 fi
 
+
 # --- Main Logic ---
 
 # Format all files (or only modified files if -g is passed)