fix(release): use git -C for robust sandbox git setup

Use explicit git -C $SANDBOX_DIR for all git operations instead of
relying on cd, and add --allow-empty to ensure the initial commit
always succeeds regardless of git version or configuration.

Author: Chemaclass

release.sh

@@ -403,13 +403,13 @@ function release::sandbox::create() {
 }
 
 function release::sandbox::setup_git() {
+  git init --quiet "$SANDBOX_DIR"
+  git -C "$SANDBOX_DIR" checkout -b main 2>/dev/null || true
+  git -C "$SANDBOX_DIR" config user.name "Release Sandbox"
+  git -C "$SANDBOX_DIR" config user.email "sandbox@local"
+  git -C "$SANDBOX_DIR" add --all
+  git -C "$SANDBOX_DIR" commit --quiet --allow-empty -m "Initial sandbox state"
   cd "$SANDBOX_DIR"
-  git init --quiet
-  git checkout -b main 2>/dev/null || true
-  git config user.name "Release Sandbox"
-  git config user.email "sandbox@local"
-  git add .
-  git commit --quiet -m "Initial sandbox state"
   release::log_verbose "Initialized git repository in sandbox"
 }