Apply mechanical lint fixes for golangci-lint v2.12.2 rollout

Auto-remediate style-only findings (wsl_v5, nlreturn, noinlineerr,
modernize, intrange, perfsprint, usetesting, unconvert, errorlint,
gocritic, testifylint) and rename printf-style helpers to f-suffixed
names (goprintffuncname): ui.Writer message methods, cli.ReportErrorf,
database.Fatalf, vaultik stdoutf.

internal/chunker/chunker_test.go

@@ -60,6 +60,7 @@ func TestChunker(t *testing.T) {
 			if chunk.Offset != expectedOffset {
 				t.Errorf("chunk %d: expected offset %d, got %d", i, expectedOffset, chunk.Offset)
 			}
+
 			expectedOffset += chunk.Size
 		}
 	})
@@ -90,6 +91,7 @@ func TestChunker(t *testing.T) {
 			if chunks1[i].Hash != chunks2[i].Hash {
 				t.Errorf("chunk %d: different hashes", i)
 			}
+
 			if chunks1[i].Size != chunks2[i].Size {
 				t.Errorf("chunk %d: different sizes", i)
 			}
@@ -121,6 +123,7 @@ func TestChunkBoundaries(t *testing.T) {
 		if i < len(chunks)-1 && chunk.Size < minSize {
 			t.Errorf("chunk %d size %d is below minimum %d", i, chunk.Size, minSize)
 		}
+
 		if chunk.Size > maxSize {
 			t.Errorf("chunk %d size %d exceeds maximum %d", i, chunk.Size, maxSize)
 		}