deps: update vendor dependencies for S3-compatible storage

Updates AWS SDK and removes Blazer B2 dependency in favor of unified
S3-compatible approach. Includes configuration examples and documentation.

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

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

vendor/github.com/aws/aws-sdk-go/service/sts/doc.go

@@ -0,0 +1,32 @@
+// Code generated by private/model/cli/gen-api/main.go. DO NOT EDIT.
+
+// Package sts provides the client and types for making API
+// requests to AWS Security Token Service.
+//
+// Security Token Service (STS) enables you to request temporary, limited-privilege
+// credentials for Identity and Access Management (IAM) users or for users that
+// you authenticate (federated users). This guide provides descriptions of the
+// STS API. For more information about using this service, see Temporary Security
+// Credentials (https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html).
+//
+// See https://docs.aws.amazon.com/goto/WebAPI/sts-2011-06-15 for more information on this service.
+//
+// See sts package documentation for more information.
+// https://docs.aws.amazon.com/sdk-for-go/api/service/sts/
+//
+// Using the Client
+//
+// To contact AWS Security Token Service with the SDK use the New function to create
+// a new service client. With that client you can make API requests to the service.
+// These clients are safe to use concurrently.
+//
+// See the SDK's documentation for more information on how to use the SDK.
+// https://docs.aws.amazon.com/sdk-for-go/api/
+//
+// See aws.Config documentation for more information on configuring SDK clients.
+// https://docs.aws.amazon.com/sdk-for-go/api/aws/#Config
+//
+// See the AWS Security Token Service client STS for more
+// information on creating client for this service.
+// https://docs.aws.amazon.com/sdk-for-go/api/service/sts/#New
+package sts