chore(git): main分支保护(pre-commit hook禁止直接提交main) + go.md补分支策略

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.githooks/pre-commit

@@ -0,0 +1,12 @@
+#!/bin/sh
+# main 分支保护：禁止直接在 main 上提交（main 是受保护的稳定线）。
+branch=$(git rev-parse --abbrev-ref HEAD 2>/dev/null)
+if [ "$branch" = "main" ]; then
+  echo "=================================================================="
+  echo " 拒绝提交：main 是受保护的稳定线，不允许直接在上面改/提交。"
+  echo " 请切到开发分支再提交：   git checkout dev"
+  echo " 确需向 main 落稳定快照：  git commit --no-verify   (并随后打 tag)"
+  echo "=================================================================="
+  exit 1
+fi
+exit 0