refactor: remove unused support for Azure blob stores

Signed-off-by: Jakob Borg <jakob@kastelo.net>

internal/blob/azureblob/azureblob.go

@@ -1,80 +0,0 @@
-// Copyright (C) 2025 The Syncthing Authors.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at https://mozilla.org/MPL/2.0/.
-
-package azureblob
-
-import (
-	"context"
-	"io"
-	"time"
-
-	stblob "github.com/syncthing/syncthing/internal/blob"
-
-	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
-	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
-	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blockblob"
-	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
-)
-
-var _ stblob.Store = (*BlobStore)(nil)
-
-type BlobStore struct {
-	client    *azblob.Client
-	container string
-}
-
-func NewBlobStore(accountName, accountKey, containerName string) (*BlobStore, error) {
-	credential, err := azblob.NewSharedKeyCredential(accountName, accountKey)
-	if err != nil {
-		return nil, err
-	}
-	url := "https://" + accountName + ".blob.core.windows.net/"
-	sc, err := azblob.NewClientWithSharedKeyCredential(url, credential, &azblob.ClientOptions{})
-	if err != nil {
-		return nil, err
-	}
-	// This errors when the container already exists, which we ignore.
-	_, _ = sc.CreateContainer(context.Background(), containerName, &container.CreateOptions{})
-	return &BlobStore{
-		client:    sc,
-		container: containerName,
-	}, nil
-}
-
-func (a *BlobStore) Upload(ctx context.Context, key string, data io.Reader) error {
-	_, err := a.client.UploadStream(ctx, a.container, key, data, &blockblob.UploadStreamOptions{})
-	return err
-}
-
-func (a *BlobStore) Download(ctx context.Context, key string, w stblob.Writer) error {
-	resp, err := a.client.DownloadStream(ctx, a.container, key, &blob.DownloadStreamOptions{})
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-	_, err = io.Copy(w, resp.Body)
-	return err
-}
-
-func (a *BlobStore) LatestKey(ctx context.Context) (string, error) {
-	opts := &azblob.ListBlobsFlatOptions{}
-	pager := a.client.NewListBlobsFlatPager(a.container, opts)
-	var latest string
-	var lastModified time.Time
-	for pager.More() {
-		page, err := pager.NextPage(ctx)
-		if err != nil {
-			return "", err
-		}
-		for _, blob := range page.Segment.BlobItems {
-			if latest == "" || blob.Properties.LastModified.After(lastModified) {
-				latest = *blob.Name
-				lastModified = *blob.Properties.LastModified
-			}
-		}
-	}
-	return latest, nil
-}