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

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

exp/delete_clauses.go

@@ -8,8 +8,8 @@ type (
 		CommonTables() []CommonTableExpression
 		CommonTablesAppend(cte CommonTableExpression) DeleteClauses
 
-		From() IdentifierExpression
-		SetFrom(table IdentifierExpression) DeleteClauses
+		From() ColumnListExpression
+		SetFrom(table ColumnListExpression) DeleteClauses
 
 		Where() ExpressionList
 		ClearWhere() DeleteClauses
@@ -33,7 +33,7 @@ type (
 	}
 	deleteClauses struct {
 		commonTables []CommonTableExpression
-		from         IdentifierExpression
+		from         ColumnListExpression
 		where        ExpressionList
 		order        ColumnListExpression
 		limit        interface{}
@@ -71,11 +71,11 @@ func (dc *deleteClauses) CommonTablesAppend(cte CommonTableExpression) DeleteCla
 	return ret
 }
 
-func (dc *deleteClauses) From() IdentifierExpression {
+func (dc *deleteClauses) From() ColumnListExpression {
 	return dc.from
 }
 
-func (dc *deleteClauses) SetFrom(table IdentifierExpression) DeleteClauses {
+func (dc *deleteClauses) SetFrom(table ColumnListExpression) DeleteClauses {
 	ret := dc.clone()
 	ret.from = table
 	return ret