next -> main (1.0.0 milestone) (#105)

Accumulating milestone branch. One squashed commit per closed issue; `next` is kept green and mergeable to `main` at any time without notice.

Landed so far:

- `chore: update golangci-lint to v2.12.2 with canonical config` (#54) — canonical v2-schema `.golangci.yml`, pins bumped in `Dockerfile` and `script/bootstrap`, tree at `0 issues.`. Three behaviour deltas are recorded in that PR's body: `Cache.StoreVariant` takes a context, `MetadataStorage.Store` no longer leaks temp files on failure, and the `signing_key` too-short error text gained a `value too short:` prefix.

Sequencing for the milestone is tracked in #103.

Reviewed-on: #105
Co-authored-by: clawbot <clawbot@noreply.example.org>

internal/seal/crypto.go

@@ -34,7 +34,8 @@ func DeriveKey(masterKey []byte, salt string) ([KeySize]byte, error) {
 
 	hkdfReader := hkdf.New(sha256.New, masterKey, []byte(salt), nil)
 
-	if _, err := io.ReadFull(hkdfReader, key[:]); err != nil {
+	_, err := io.ReadFull(hkdfReader, key[:])
+	if err != nil {
 		return key, ErrKeyDerivation
 	}
 
@@ -46,7 +47,9 @@ func DeriveKey(masterKey []byte, salt string) ([KeySize]byte, error) {
 func Encrypt(key [KeySize]byte, plaintext []byte) (string, error) {
 	// Generate random nonce
 	var nonce [NonceSize]byte
-	if _, err := rand.Read(nonce[:]); err != nil {
+
+	_, err := rand.Read(nonce[:])
+	if err != nil {
 		return "", err
 	}