Fix lint errors and bump golangci-lint to v2/action v9

- Migrate .golangci.yml to golangci-lint v2 config format
- Bump golangci-lint-action from v6 (Node 20, deprecated) to v9 (Node 24)
- Fix errcheck: check fmt.Fscanln and fmt.Sscanf return values
- Fix ineffassign: replace unused vars with _ in test files
- Fix revive unused-parameter: rename unused cmd/args/r/c params to _
- Fix revive empty-block: invert if condition in push command
- Fix revive redefines-builtin-id: rename 'clear' to 'clearsigned'
- Fix revive blank-imports: add comment on modernc.org/sqlite import
- Fix unused: remove unused 'suite' and 'gen' fields from cache entry

shared/apt/apt.go

@@ -115,11 +115,11 @@ func Generate(s *Suite, signer Signer) (*Indices, error) {
 	idx.Release = release
 
 	if signer != nil {
-		clear, err := signer.ClearSign(release)
+		clearsigned, err := signer.ClearSign(release)
 		if err != nil {
 			return nil, fmt.Errorf("clearsign: %w", err)
 		}
-		idx.InRelease = clear
+		idx.InRelease = clearsigned
 		det, err := signer.DetachedSign(release)
 		if err != nil {
 			return nil, fmt.Errorf("detach sign: %w", err)

shared/config/config.go

@@ -190,13 +190,13 @@ func (c *Config) Validate() error {
 	return nil
 }
 
-func set(c *Config, env string, dst *string) {
+func set(_ *Config, env string, dst *string) {
 	if v, ok := os.LookupEnv(env); ok && v != "" {
 		*dst = v
 	}
 }
 
-func setInt(c *Config, env string, dst *int) {
+func setInt(_ *Config, env string, dst *int) {
 	if v, ok := os.LookupEnv(env); ok && v != "" {
 		if n, err := strconv.Atoi(v); err == nil {
 			*dst = n
@@ -204,7 +204,7 @@ func setInt(c *Config, env string, dst *int) {
 	}
 }
 
-func setInt64(c *Config, env string, dst *int64) {
+func setInt64(_ *Config, env string, dst *int64) {
 	if v, ok := os.LookupEnv(env); ok && v != "" {
 		if n, err := strconv.ParseInt(v, 10, 64); err == nil {
 			*dst = n
@@ -212,7 +212,7 @@ func setInt64(c *Config, env string, dst *int64) {
 	}
 }
 
-func setBool(c *Config, env string, dst *bool) {
+func setBool(_ *Config, env string, dst *bool) {
 	if v, ok := os.LookupEnv(env); ok && v != "" {
 		if b, err := strconv.ParseBool(v); err == nil {
 			*dst = b

shared/db/db.go

@@ -14,7 +14,7 @@ import (
 	"strings"
 	"time"
 
-	_ "modernc.org/sqlite"
+	_ "modernc.org/sqlite" // register the pure-Go SQLite driver
 )
 
 //go:embed all:migrations

shared/deb/deb.go

@@ -164,7 +164,9 @@ func readAR(r io.Reader) ([]arMember, error) {
 		name = strings.TrimSuffix(name, "/")
 		sizeStr := strings.TrimSpace(string(header[48:58]))
 		var size int64
-		fmt.Sscanf(sizeStr, "%d", &size)
+		if _, err := fmt.Sscanf(sizeStr, "%d", &size); err != nil {
+			return nil, fmt.Errorf("parse ar member size %q: %w", sizeStr, err)
+		}
 		if size < 0 {
 			return nil, fmt.Errorf("negative ar member size")
 		}