feat: reword phase to epic, update mkdocs

docs/content/stories/epic5/5.3-blob-storage.md

@@ -0,0 +1,65 @@
+# Story 5.3: Blob Storage System
+
+## Metadata
+- **Story ID**: 5.3
+- **Title**: Blob Storage System
+- **Epic**: 5 - Infrastructure Adapters
+- **Status**: Pending
+- **Priority**: Medium
+- **Estimated Time**: 5-6 hours
+- **Dependencies**: 1.1, 1.5
+
+## Goal
+Implement a complete blob storage system using S3 with a clean interface for file upload, download, and management.
+
+## Description
+This story implements S3-based blob storage with support for file uploads, downloads, signed URLs, and file deletion. It includes an API endpoint for file uploads.
+
+## Deliverables
+
+### 1. Blob Storage Interface (`pkg/infra/blob/blob.go`)
+- `BlobStore` interface with:
+  - `Upload(ctx context.Context, key string, data []byte) error`
+  - `Download(ctx context.Context, key string) ([]byte, error)`
+  - `Delete(ctx context.Context, key string) error`
+  - `GetSignedURL(ctx context.Context, key string, ttl time.Duration) (string, error)`
+  - `Exists(ctx context.Context, key string) (bool, error)`
+
+### 2. S3 Implementation (`internal/infra/blob/s3_store.go`)
+- AWS S3 client setup
+- All interface methods implemented
+- Error handling
+- Content type detection
+
+### 3. File Upload API
+- `POST /api/v1/files/upload` - Upload file
+- File validation
+- Size limits
+- Content type validation
+
+### 4. Configuration
+- S3 config in `config/default.yaml`:
+  - Bucket name
+  - Region
+  - Credentials (or use IAM role)
+
+### 5. DI Integration
+- Provider function for BlobStore
+- Register in DI container
+
+## Acceptance Criteria
+- [ ] Blob storage interface is defined
+- [ ] S3 implementation works correctly
+- [ ] Files can be uploaded and downloaded
+- [ ] Signed URLs are generated correctly
+- [ ] File upload API works
+- [ ] Configuration is loaded from config
+- [ ] Blob store is injectable via DI
+
+## Files to Create/Modify
+- `pkg/infra/blob/blob.go` - Blob storage interface
+- `internal/infra/blob/s3_store.go` - S3 implementation
+- `internal/infra/blob/handler.go` - File upload handler
+- `internal/di/providers.go` - Add blob store provider
+- `config/default.yaml` - Add S3 config
+