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/main.go

@@ -119,6 +119,14 @@ func Run(
 	// Initialize the user interface
 	l.UserInterface()
 
+	// Initialize Blossom blob storage server
+	if l.blossomServer, err = initializeBlossomServer(ctx, cfg, db); err != nil {
+		log.E.F("failed to initialize blossom server: %v", err)
+		// Continue without blossom server
+	} else if l.blossomServer != nil {
+		log.I.F("blossom blob storage server initialized")
+	}
+
 	// Ensure a relay identity secret key exists when subscriptions and NWC are enabled
 	if cfg.SubscriptionEnabled && cfg.NWCUri != "" {
 		if skb, e := db.GetOrCreateRelayIdentitySecret(); e != nil {