rag/treesitter: add nocgo build support

Allow building without CGO for applications that do not use RAG.
DocumentProcessor returns an error when built without CGO and RAG is used.

Author: shaj13

pkg/rag/treesitter/treesitter.go

@@ -1,3 +1,5 @@
+//go:build cgo
+
 package treesitter
 
 import (

pkg/rag/treesitter/treesitter_nocgo.go

@@ -0,0 +1,24 @@
+//go:build !cgo
+
+package treesitter
+
+import (
+	"errors"
+
+	"github.com/docker/docker-agent/pkg/rag/chunk"
+)
+
+// DocumentProcessor implements chunk.DocumentProcessor and always returns an
+// error when the application is built without CGO and uses RAG. For applications
+// that do not use RAG, this allows building without any CGO requirement.
+type DocumentProcessor struct{}
+
+// NewDocumentProcessor creates a new DocumentProcessor.
+func NewDocumentProcessor(_, _ int, _ bool) *DocumentProcessor {
+	return &DocumentProcessor{}
+}
+
+// Process implements chunk.DocumentProcessor.
+func (p *DocumentProcessor) Process(_ string, _ []byte) ([]chunk.Chunk, error) {
+	return nil, errors.New("rag/treesitter: document processor must be built with CGO_ENABLED=1")
+}