feat(store): add blob, file, folder, and upload stores

Add BlobStore (ref counting), FileStore (soft delete + pagination), FolderStore (materialized path), UploadStore (idempotent upsert), and update AutoMigrate.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/store/upload_store.go

@@ -0,0 +1,117 @@
+package store
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"gcy_hpc_server/internal/model"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+)
+
+// UploadStore manages upload sessions and chunks with idempotent upsert support.
+type UploadStore struct {
+	db *gorm.DB
+}
+
+// NewUploadStore creates a new UploadStore.
+func NewUploadStore(db *gorm.DB) *UploadStore {
+	return &UploadStore{db: db}
+}
+
+// CreateSession inserts a new upload session.
+func (s *UploadStore) CreateSession(ctx context.Context, session *model.UploadSession) error {
+	return s.db.WithContext(ctx).Create(session).Error
+}
+
+// GetSession returns an upload session by ID. Returns (nil, nil) if not found.
+func (s *UploadStore) GetSession(ctx context.Context, id int64) (*model.UploadSession, error) {
+	var session model.UploadSession
+	err := s.db.WithContext(ctx).First(&session, id).Error
+	if errors.Is(err, gorm.ErrRecordNotFound) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &session, nil
+}
+
+// GetSessionWithChunks returns an upload session along with its chunks ordered by chunk_index.
+func (s *UploadStore) GetSessionWithChunks(ctx context.Context, id int64) (*model.UploadSession, []model.UploadChunk, error) {
+	session, err := s.GetSession(ctx, id)
+	if err != nil {
+		return nil, nil, err
+	}
+	if session == nil {
+		return nil, nil, nil
+	}
+
+	var chunks []model.UploadChunk
+	if err := s.db.WithContext(ctx).Where("session_id = ?", id).Order("chunk_index ASC").Find(&chunks).Error; err != nil {
+		return nil, nil, err
+	}
+	return session, chunks, nil
+}
+
+// UpdateSessionStatus updates the status field of an upload session.
+// Returns gorm.ErrRecordNotFound if no row was affected.
+func (s *UploadStore) UpdateSessionStatus(ctx context.Context, id int64, status string) error {
+	result := s.db.WithContext(ctx).Model(&model.UploadSession{}).Where("id = ?", id).Update("status", status)
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return gorm.ErrRecordNotFound
+	}
+	return nil
+}
+
+// ListExpiredSessions returns sessions that are not in a terminal state and have expired.
+func (s *UploadStore) ListExpiredSessions(ctx context.Context) ([]model.UploadSession, error) {
+	var sessions []model.UploadSession
+	err := s.db.WithContext(ctx).
+		Where("status NOT IN ?", []string{"completed", "cancelled", "expired"}).
+		Where("expires_at < ?", time.Now()).
+		Find(&sessions).Error
+	return sessions, err
+}
+
+// DeleteSession removes all chunks for a session, then the session itself.
+func (s *UploadStore) DeleteSession(ctx context.Context, id int64) error {
+	if err := s.db.WithContext(ctx).Where("session_id = ?", id).Delete(&model.UploadChunk{}).Error; err != nil {
+		return fmt.Errorf("delete chunks: %w", err)
+	}
+	result := s.db.WithContext(ctx).Delete(&model.UploadSession{}, id)
+	return result.Error
+}
+
+// UpsertChunk inserts a chunk or updates it if the (session_id, chunk_index) pair already exists.
+// Uses GORM clause.OnConflict for dialect-neutral upsert (works with both SQLite and MySQL).
+func (s *UploadStore) UpsertChunk(ctx context.Context, chunk *model.UploadChunk) error {
+	return s.db.WithContext(ctx).Clauses(clause.OnConflict{
+		Columns:   []clause.Column{{Name: "session_id"}, {Name: "chunk_index"}},
+		DoUpdates: clause.AssignmentColumns([]string{"minio_key", "sha256", "size", "status", "updated_at"}),
+	}).Create(chunk).Error
+}
+
+// GetUploadedChunkIndices returns the chunk indices that have been successfully uploaded.
+func (s *UploadStore) GetUploadedChunkIndices(ctx context.Context, sessionID int64) ([]int, error) {
+	var indices []int
+	err := s.db.WithContext(ctx).Model(&model.UploadChunk{}).
+		Where("session_id = ? AND status = ?", sessionID, "uploaded").
+		Pluck("chunk_index", &indices).Error
+	return indices, err
+}
+
+// CountUploadedChunks returns the number of chunks with status "uploaded" for a session.
+func (s *UploadStore) CountUploadedChunks(ctx context.Context, sessionID int64) (int, error) {
+	var count int64
+	err := s.db.WithContext(ctx).Model(&model.UploadChunk{}).
+		Where("session_id = ? AND status = ?", sessionID, "uploaded").
+		Count(&count).Error
+	return int(count), err
+}