Remediate all lint findings under the canonical golangci-lint config

Fix every finding surfaced by the canonical .golangci.yml with
golangci-lint v2.12.2 (refs #61), behavior-preserving throughout:

- err113: dynamic errors replaced with package-level sentinels and %w
  wrapping; direct comparisons converted to errors.Is
- goprintffuncname: printf-style helpers renamed with an f suffix
  (ui.Writer message methods, cli.ReportErrorf, database.Fatalf,
  vaultik stdoutf) and all call sites updated
- revive: stuttering type names renamed (blob.Handler, blob.WithReader,
  blob.ChunkPosition, storage.URL, storage.Info), doc comments added,
  unused parameters blanked, package comments added
- contextcheck/noctx: ctx threaded through blob.Packer
  (AddChunk/Flush/FinalizeBlob/PackChunks) and scanner call sites;
  context-aware exec and sql variants used
- funlen/cyclop/gocognit/nestif/dupl: oversized or duplicated
  functions split into focused helpers across production and test code
- paralleltest/tparallel/thelper/usetesting/testpackage: tests
  parallelized where safe (global log.Initialize kept in the serial
  phase), helpers marked, t.TempDir adopted, external test packages
  where only exported API is used
- gosec: integer conversions clamped or justified, header timeouts
  added, remaining findings suppressed with per-site justifications
- mnd/goconst/lll/wsl_v5/nlreturn/noinlineerr/errcheck and other
  mechanical findings fixed directly

Remove the deprecated log.LogOptions alias (callers migrated to
log.Options). make check is green.

internal/s3/client.go

@@ -1,3 +1,5 @@
+// Package s3 wraps the AWS S3 SDK with a simplified client for vaultik's
+// bucket-and-prefix scoped object operations.
 package s3
 
 import (
@@ -42,7 +44,7 @@ type Config struct {
 // Used to suppress SDK warnings about checksums.
 type nopLogger struct{}
 
-func (nopLogger) Logf(classification logging.Classification, format string, v ...any) {}
+func (nopLogger) Logf(_ logging.Classification, _ string, _ ...any) {}
 
 // NewClient creates a new S3 client with the provided configuration.
 // It establishes a connection to the S3-compatible storage service and
@@ -105,13 +107,18 @@ type ProgressCallback func(bytesUploaded int64) error
 // The size parameter must be the exact size of the data to upload.
 // The progress callback is called periodically with the number of bytes uploaded.
 // Returns an error if the upload fails.
-func (c *Client) PutObjectWithProgress(ctx context.Context, key string, data io.Reader, size int64, progress ProgressCallback) error {
+func (c *Client) PutObjectWithProgress(
+	ctx context.Context, key string, data io.Reader,
+	size int64, progress ProgressCallback,
+) error {
 	fullKey := c.prefix + key
 
+	// uploadPartSize is 10MB for better progress granularity.
+	const uploadPartSize = 10 * 1024 * 1024
+
 	// Create an uploader with the S3 client
 	uploader := manager.NewUploader(c.s3Client, func(u *manager.Uploader) {
-		// Set part size to 10MB for better progress granularity
-		u.PartSize = 10 * 1024 * 1024
+		u.PartSize = uploadPartSize
 	})
 
 	// Create a progress reader that tracks upload progress
@@ -241,7 +248,9 @@ type ObjectInfo struct {
 // listing is complete or an error occurs. If an error occurs, it will be
 // sent as the last item with the Err field set. The recursive parameter
 // is currently unused but reserved for future use.
-func (c *Client) ListObjectsStream(ctx context.Context, prefix string, recursive bool) <-chan ObjectInfo {
+func (c *Client) ListObjectsStream(
+	ctx context.Context, prefix string, _ bool,
+) <-chan ObjectInfo {
 	ch := make(chan ObjectInfo)
 
 	go func() {