fix(build): resolve incorrect git ref path causing unnecessary recompilation (#56)

The build script was constructing the git ref path by joining the ref
(e.g. refs/heads/main) to the repo root instead of the .git directory.
This produced a non-existent path like /repo/refs/heads/main instead of
/repo/.git/refs/heads/main. Since cargo treats a missing rerun-if-changed
file as always stale, streamkit-server was recompiled on every build
even with no code changes.

Fix: use head_path.parent() (the .git dir) instead of going up two
levels to the repo root.

Co-authored-by: StreamKit Devin <devin@streamkit.dev>
Co-authored-by: Claudio Costa <cstcld91@gmail.com>

Author: 3 people

apps/skit/build.rs

@@ -23,8 +23,8 @@ fn main() {
 
         if let Ok(head_ref) = fs::read_to_string(head_path) {
             if let Some(reference) = head_ref.trim().strip_prefix("ref: ") {
-                if let Some(repo_root) = head_path.parent().and_then(|dir| dir.parent()) {
-                    let ref_path = repo_root.join(reference);
+                if let Some(git_dir) = head_path.parent() {
+                    let ref_path = git_dir.join(reference);
                     println!("cargo:rerun-if-changed={}", ref_path.display());
                 }
             }