docs: Add CLAUDE.md with codebase guidance

Create comprehensive documentation for future Claude Code instances working in this repository, including:
- Development commands for testing, building, and code quality
- Core architecture overview of the SQL query builder system
- Directory structure and component explanations
- Testing patterns and conventions
- Key dependencies and their purposes

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

exec/query_hooks.go

@@ -0,0 +1,7 @@
+package exec
+
+// Hooks 钩子实例
+type Hooks interface {
+	Before(dataset interface{}) error
+	After(dataset interface{}, result interface{}) error
+}