Add codespell support with configuration and fixes (#21807)

Co-authored-by: Claude Code 2.1.142 / Claude Opus 4.7 <noreply@anthropic.com>

internal/repository/packer_manager.go

@@ -74,7 +74,7 @@ func (r *packerManager) Flush(ctx context.Context) error {
 
 // mergePackers merges small pack files before those are uploaded by Flush(). The main
 // purpose of this method is to reduce information leaks if a small file is backed up
-// and the blobs end up in spearate pack files. If the file only consists of two blobs
+// and the blobs end up in separate pack files. If the file only consists of two blobs
 // this would leak the size of the individual blobs.
 func (r *packerManager) mergePackers() ([]*packer, error) {
 	pendingPackers := []*packer{}

internal/repository/prune.go

@@ -342,7 +342,7 @@ func calculateTargetPacksize(opts PruneOptions, indexPack map[restic.ID]packInfo
 			return cmp.Compare(a.size, b.size)
 		})
 
-		// Using the approximatelly 3rd percentile is just a heuristic and may not always be the optimal choice.
+		// Using the approximately 3rd percentile is just a heuristic and may not always be the optimal choice.
 		// However, using a low percentile ensures that only a small fraction of the repository
 		// may end up being repacked. By using 80% of that perecentile or the minimum pack size,
 		// we ensure that no repacking happens if the repository already has no small pack files.

internal/repository/prune_test.go

@@ -133,7 +133,7 @@ func TestPruneSmall(t *testing.T) {
 
 	keep := restic.NewBlobSet()
 	rtest.OK(t, repo.WithBlobUploader(context.TODO(), func(ctx context.Context, uploader restic.BlobSaverWithAsync) error {
-		// we need a minum of 11 packfiles, each packfile will be about 5 Mb long
+		// we need a minimum of 11 packfiles, each packfile will be about 5 Mb long
 		for i := 0; i < numBlobsCreated; i++ {
 			buf := make([]byte, blobSize)
 			random.Read(buf)