Add versioning, update tool, and soft-delete

Schema: public_id + version columns with UNIQUE constraint,
delete_timestamp for soft-delete.

Tools: store_flashcard accepts optional public_id, update_flashcard
creates a new version preserving history, delete_flashcard inserts
a tombstone row and removes the Qdrant point.

Qdrant: point ID is public_id (only latest version indexed).

qdrant.go

@@ -8,17 +8,20 @@ import (
 	"github.com/qdrant/go-client/qdrant"
 )
 
-const collectionName = "knowledge"
+const collectionName = "flashcard"
 
 type entry struct {
-	ID      int64    `json:"id"`
-	Note    string   `json:"note"`
-	Repos   []string `json:"repos,omitempty"`
-	Host    string   `json:"host,omitempty"`
-	Tags    []string `json:"tags,omitempty"`
-	User    string   `json:"user,omitempty"`
-	Context string   `json:"context,omitempty"`
-	Created string   `json:"created"`
+	ID        int64    `json:"_id"`
+	PublicID  int64    `json:"public_id"`
+	Version   int      `json:"version"`
+	Note      string   `json:"note"`
+	Repos     []string `json:"repos,omitempty"`
+	Host      string   `json:"host,omitempty"`
+	Tags      []string `json:"tags,omitempty"`
+	User      string   `json:"user,omitempty"`
+	Context         string   `json:"context,omitempty"`
+	DeleteTimestamp string   `json:"delete_timestamp,omitempty"`
+	Created         string   `json:"created"`
 }
 
 type searchResult struct {
@@ -58,22 +61,24 @@ func (s *qdrantStore) ensureCollection(ctx context.Context) error {
 	return nil
 }
 
-func (s *qdrantStore) index(ctx context.Context, id int64, note string) error {
+func (s *qdrantStore) index(ctx context.Context, id, publicID int64, version int, note string) error {
 	vec, err := s.embedder.embedText(ctx, note)
 	if err != nil {
 		return fmt.Errorf("embed text: %w", err)
 	}
 
 	payload := map[string]*qdrant.Value{
-		"id":      qdrant.NewValueString(strconv.FormatInt(id, 10)),
-		"content": qdrant.NewValueString(note),
+		"_id":       qdrant.NewValueString(strconv.FormatInt(id, 10)),
+		"public_id": qdrant.NewValueString(strconv.FormatInt(publicID, 10)),
+		"version":   qdrant.NewValueInt(int64(version)),
+		"content":   qdrant.NewValueString(note),
 	}
 
 	_, err = s.client.Upsert(ctx, &qdrant.UpsertPoints{
 		CollectionName: collectionName,
 		Points: []*qdrant.PointStruct{
 			{
-				Id:      qdrant.NewIDNum(uint64(id)),
+				Id:      qdrant.NewIDNum(uint64(publicID)),
 				Vectors: qdrant.NewVectors(vec...),
 				Payload: payload,
 			},
@@ -86,6 +91,21 @@ func (s *qdrantStore) index(ctx context.Context, id int64, note string) error {
 	return nil
 }
 
+func (s *qdrantStore) delete(ctx context.Context, publicID int64) error {
+	wait := true
+	_, err := s.client.Delete(ctx, &qdrant.DeletePoints{
+		CollectionName: collectionName,
+		Wait:           &wait,
+		Points: qdrant.NewPointsSelector(
+			qdrant.NewIDNum(uint64(publicID)),
+		),
+	})
+	if err != nil {
+		return fmt.Errorf("delete point: %w", err)
+	}
+	return nil
+}
+
 func (s *qdrantStore) search(ctx context.Context, query string, limit uint64) ([]searchResult, error) {
 	vec, err := s.embedder.embedText(ctx, query)
 	if err != nil {
@@ -113,7 +133,7 @@ func (s *qdrantStore) search(ctx context.Context, query string, limit uint64) ([
 		}
 
 		if payload := pt.GetPayload(); payload != nil {
-			if v, ok := payload["id"]; ok {
+			if v, ok := payload["_id"]; ok {
 				if n, err := strconv.ParseInt(v.GetStringValue(), 10, 64); err == nil {
 					r.Entry.ID = n
 				}