Add Blossom blob storage server and subscription management

- Introduced the `initializeBlossomServer` function to set up the Blossom blob storage server with dynamic base URL handling and ACL configuration.
- Implemented the `blossomHandler` method to manage incoming requests to the Blossom API, ensuring proper URL handling and context management.
- Enhanced the `PaymentProcessor` to support Blossom service levels, allowing for subscription extensions based on payment metadata.
- Added methods for parsing and validating Blossom service levels, including storage quota management and subscription extension logic.
- Updated the configuration to include Blossom service level settings, facilitating dynamic service level management.
- Integrated storage quota checks in the blob upload process to prevent exceeding allocated limits.
- Refactored existing code to improve organization and maintainability, including the removal of unused blob directory configurations.
- Added tests to ensure the robustness of new functionalities and maintain existing behavior across blob operations.

app/config/config.go

@@ -52,6 +52,9 @@ type C struct {
 	RelayAddresses      []string      `env:"ORLY_RELAY_ADDRESSES" usage:"comma-separated list of websocket addresses for this relay (e.g., wss://relay.example.com,wss://backup.example.com)"`
 	FollowListFrequency time.Duration `env:"ORLY_FOLLOW_LIST_FREQUENCY" usage:"how often to fetch admin follow lists (default: 1h)" default:"1h"`
 
+	// Blossom blob storage service level settings
+	BlossomServiceLevels string `env:"ORLY_BLOSSOM_SERVICE_LEVELS" usage:"comma-separated list of service levels in format: name:storage_mb_per_sat_per_month (e.g., basic:1,premium:10)"`
+
 	// Web UI and dev mode settings
 	WebDisableEmbedded bool   `env:"ORLY_WEB_DISABLE" default:"false" usage:"disable serving the embedded web UI; useful for hot-reload during development"`
 	WebDevProxyURL     string `env:"ORLY_WEB_DEV_PROXY_URL" usage:"when ORLY_WEB_DISABLE is true, reverse-proxy non-API paths to this dev server URL (e.g. http://localhost:5173)"`