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>

schema/blueprint.go

@@ -10,10 +10,11 @@ type Blueprint struct {
 	table     string              // the table the blueprint describes.
 	columns   []*ColumnDefinition // columns that should be added to the table
 	commands  []*Command          //
-	temporary bool                // Whether to make the table temporary.
-	charset   string              // The default character set that should be used for the table.
-	collation string              // The collation that should be used for the table.
-	engine    string              // The engine that should be used for the table.
+	Temporary bool                // Whether to make the table temporary.
+	Charset   string              // The default character set that should be used for the table.
+	Collation string              // The collation that should be used for the table.
+	Engine    string              // The engine that should be used for the table.
+	Comment   string
 }
 
 type Command struct {
@@ -30,7 +31,7 @@ type CommandOptions struct {
 }
 
 func NewBlueprint(table string) *Blueprint {
-	return &Blueprint{table: table, charset: "utf8mb4", collation: "utf8mb4_general_ci"}
+	return &Blueprint{table: table}
 }
 
 // 字符串
@@ -263,21 +264,17 @@ func (this *Blueprint) Create() *Command {
 	return this.addCommand("create", CommandOptions{})
 }
 
-// 设置临时表标记
-func (this *Blueprint) Temporary() {
-	this.temporary = true
-}
-
-// 设置表字符集
-func (this *Blueprint) Charset(charset string) {
-	this.charset = charset
-}
-
 // 修改表名
 func (this *Blueprint) Rename(to string) *Command {
 	return this.addCommand("rename", CommandOptions{To: to})
 }
 
+// 修改表备注
+func (this *Blueprint) ModifyComment(comment string) *Command {
+	this.Comment = comment
+	return this.addCommand("modifyComment", CommandOptions{})
+}
+
 // 删除表
 func (this *Blueprint) Drop() *Command {
 	return this.addCommand("drop", CommandOptions{})
@@ -307,6 +304,8 @@ func (this *Blueprint) ToSql(sc Schema) (statements []string) {
 			statements = append(statements, sc.CompileDropColumn(this)...)
 		case "rename":
 			statements = append(statements, sc.CompileRename(this)...)
+		case "modifyComment":
+			statements = append(statements, sc.CompileModifyComment(this)...)
 		}
 	}
 
@@ -420,26 +419,10 @@ func (this *Blueprint) GetCommands() []*Command {
 	return this.commands
 }
 
-func (this *Blueprint) IsTemporary() bool {
-	return this.temporary
-}
-
 func (this *Blueprint) GetTable() string {
 	return this.table
 }
 
-func (this *Blueprint) GetCharset() string {
-	return this.charset
-}
-
-func (this *Blueprint) GetEngine() string {
-	return this.engine
-}
-
-func (this *Blueprint) GetCollation() string {
-	return this.collation
-}
-
 // 命令类型
 func (this *Command) Command() string {
 	return this.Type