fix(githooks): restore cd-to-repo-top before NVM load

Without cd, git rev-parse --show-toplevel fails inside .git/
with 'must be run in a work tree', causing init_log_file to
write to /logs/post-receive.log (root path), and copy_env_by_branch
to fail with 'cannot stat env-example/...'.

.githooks/post-receive

@@ -14,6 +14,18 @@
 #   - **不**用 set -e —— 各步**自**己处理错**误**（env 不**存**在 / build 失败 / 旧**进**程**不**存**在）→ 让 deploy 错**误****不**挡 git push
 
 
+# git-receive-pack 调 hook 时 CWD **可**能是 `.git/` 内**部**，
+# `git rev-parse --show-toplevel` 会**报**错 `must be run in a work tree`。
+# 解**法**：**用** `git rev-parse --absolute-git-dir` **取**得**绝**对 .git **路**径，
+# 然后 dirname **得**到 repo **顶**层。**这**两个调**用**在 .git/ 内**部**也都**能**成**功**。
+GIT_DIR_ABS="$(git rev-parse --absolute-git-dir 2>/dev/null || true)"
+if [ -n "$GIT_DIR_ABS" ] && [ "$GIT_DIR_ABS" != ".git" ]; then
+    REPO_TOPLEVEL="$(cd "$GIT_DIR_ABS/.." && pwd)"
+else
+    REPO_TOPLEVEL="$PWD"
+fi
+cd "$REPO_TOPLEVEL" || { echo "FATAL: cannot cd to $REPO_TOPLEVEL" >&2; exit 1; }
+
 # 同 .bashrc **里**的 NVM **加**载逻辑
 export NVM_DIR="$HOME/.nvm"
 [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm