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>

sqlgen/delete_sql_generator.go

@@ -1,9 +1,9 @@
 package sqlgen
 
 import (
-	"git.fsdpf.net/go/db/v2/exp"
-	"git.fsdpf.net/go/db/v2/internal/errors"
-	"git.fsdpf.net/go/db/v2/internal/sb"
+	"git.fsdpf.net/go/db/exp"
+	"git.fsdpf.net/go/db/internal/errors"
+	"git.fsdpf.net/go/db/internal/sb"
 )
 
 type (
@@ -67,6 +67,14 @@ func (dsg *deleteSQLGenerator) Generate(b sb.SQLBuilder, clauses exp.DeleteClaus
 func (dsg *deleteSQLGenerator) DeleteBeginSQL(b sb.SQLBuilder, from exp.ColumnListExpression, multiTable bool) {
 	b.Write(dsg.DialectOptions().DeleteClause)
 	if multiTable && dsg.DialectOptions().SupportsDeleteTableHint {
-		dsg.SourcesSQL(b, from)
+		_from := exp.NewColumnListExpression()
+		for _, col := range from.Columns() {
+			if aliased, ok := col.(exp.AliasedExpression); ok {
+				_from = _from.Append(aliased.GetAs())
+			} else {
+				_from = _from.Append(col)
+			}
+		}
+		dsg.SourcesSQL(b, _from)
 	}
 }