feat: add storage module with S3 support and development tooling

Create shared storage module for AWS S3 operations with comprehensive
development infrastructure:

Core Features:
- S3 interface with two upload patterns (manager and direct)
- Presigned URL generation with 15-minute expiration
- Support for multipart uploads and direct PutObject
- Comprehensive test coverage (8 tests, 70.4% coverage)
- Generic implementation without project-specific dependencies

Development Tooling:
- .editorconfig for consistent editor settings
- .pre-commit-config.yaml with Go linters and formatters
- .golangci.yml for golangci-lint configuration
- commitlint.config.js for conventional commit validation
- cliff.toml for automated changelog generation (v0.0.1)
- renovate.json for automated dependency updates
- .gitlab-ci.yml for CI/CD pipeline

CI/CD Pipeline:
- Automated testing with race detection
- Coverage tracking and Codecov integration
- Vulnerability scanning with govulncheck
- Pre-commit validation gates
- Release automation

Module exports:
- New(bucket) - Upload manager pattern for large files
- NewS3(cfg, bucket) - Direct upload pattern
- Store(path, content, contentType) - Upload and get presigned URL

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

s3.go

@@ -0,0 +1,125 @@
+package storage
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/feature/s3/manager"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+)
+
+// Uploader is the interface for uploading objects to S3 using the upload manager
+type Uploader interface {
+	Upload(ctx context.Context, input *s3.PutObjectInput, opts ...func(*manager.Uploader)) (*manager.UploadOutput, error)
+}
+
+// DirectUploader is the interface for uploading objects directly to S3
+type DirectUploader interface {
+	PutObject(ctx context.Context, params *s3.PutObjectInput, optFns ...func(*s3.Options)) (*s3.PutObjectOutput, error)
+}
+
+// Presigner is the interface for generating presigned URLs
+type Presigner interface {
+	PresignGetObject(ctx context.Context, params *s3.GetObjectInput, optFns ...func(*s3.PresignOptions)) (*v4.PresignedHTTPRequest, error)
+}
+
+// S3 provides storage operations for AWS S3
+type S3 struct {
+	bucket          string
+	svc             Uploader
+	directSvc       DirectUploader
+	presigner       Presigner
+	useDirectUpload bool
+}
+
+// Store uploads content to S3 and returns a presigned URL valid for 15 minutes
+func (s *S3) Store(path string, content io.Reader, contentType string) (string, error) {
+	if s.useDirectUpload {
+		return s.storeWithDirectUpload(path, content, contentType)
+	}
+	return s.storeWithManager(path, content, contentType)
+}
+
+func (s *S3) storeWithManager(path string, content io.Reader, contentType string) (string, error) {
+	out, err := s.svc.Upload(context.Background(), &s3.PutObjectInput{
+		Bucket: aws.String(s.bucket),
+		Key:    aws.String(path),
+		Body:   content,
+	})
+	if err != nil {
+		return "", err
+	}
+	presignedUrl, err := s.presigner.PresignGetObject(context.Background(),
+		&s3.GetObjectInput{
+			Bucket:              aws.String(s.bucket),
+			Key:                 aws.String(*out.Key),
+			ResponseContentType: aws.String(contentType),
+		},
+		s3.WithPresignExpires(time.Minute*15),
+	)
+	if err != nil {
+		return "", err
+	}
+
+	return presignedUrl.URL, nil
+}
+
+func (s *S3) storeWithDirectUpload(path string, content io.Reader, contentType string) (string, error) {
+	// Upload file to S3
+	_, err := s.directSvc.PutObject(context.Background(), &s3.PutObjectInput{
+		Bucket:      aws.String(s.bucket),
+		Key:         aws.String(path),
+		Body:        content,
+		ContentType: aws.String(contentType),
+	})
+	if err != nil {
+		return "", err
+	}
+
+	// Generate presigned URL valid for 15 minutes
+	req, err := s.presigner.PresignGetObject(context.Background(), &s3.GetObjectInput{
+		Bucket: aws.String(s.bucket),
+		Key:    aws.String(path),
+	}, s3.WithPresignExpires(15*time.Minute))
+	if err != nil {
+		return "", err
+	}
+
+	return req.URL, nil
+}
+
+// New creates a new S3 storage instance using the upload manager
+// This loads AWS config from the default locations and is suitable for most use cases
+func New(bucket string) (*S3, error) {
+	cfg, err := config.LoadDefaultConfig(context.Background())
+	if err != nil {
+		return nil, err
+	}
+	client := s3.NewFromConfig(cfg)
+	uploader := manager.NewUploader(client, func(u *manager.Uploader) {
+		u.PartSize = 5 * 1024 * 1024
+	})
+	presignClient := s3.NewPresignClient(client)
+	return &S3{
+		bucket:          bucket,
+		svc:             uploader,
+		presigner:       presignClient,
+		useDirectUpload: false,
+	}, nil
+}
+
+// NewS3 creates a new S3 storage instance using direct PutObject
+// This is useful when you want more control over the AWS configuration
+func NewS3(cfg aws.Config, bucket string) *S3 {
+	client := s3.NewFromConfig(cfg)
+	return &S3{
+		bucket:          bucket,
+		directSvc:       client,
+		presigner:       s3.NewPresignClient(client),
+		useDirectUpload: true,
+	}
+}