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/cli/app_test.go

@@ -1,4 +1,4 @@
-package cli
+package cli //nolint:testpackage // needs access to unexported cleanStartupError
 
 import (
 	"errors"
@@ -6,6 +6,8 @@ import (
 )
 
 func TestCleanStartupError(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		name string
 		in   string
@@ -13,7 +15,18 @@ func TestCleanStartupError(t *testing.T) {
 	}{
 		{
 			name: "real fx error chain",
-			in:   `could not build arguments for function "sneak.berlin/go/vaultik/internal/cli".newSnapshotCreateCommand.func1.1 (/Users/user/dev/vaultik/internal/cli/snapshot.go:71): failed to build *vaultik.Vaultik: could not build arguments for function "sneak.berlin/go/vaultik/internal/vaultik".New (/Users/user/dev/vaultik/internal/vaultik/vaultik.go:59): failed to build storage.Storer: received non-nil error from function "sneak.berlin/go/vaultik/internal/storage".NewStorer (/Users/user/dev/vaultik/internal/storage/module.go:23): creating base path: mkdir /Volumes/BACKUPS: permission denied`,
+			in: `could not build arguments for function ` +
+				`"sneak.berlin/go/vaultik/internal/cli".newSnapshotCreateCommand.func1.1 ` +
+				`(/Users/user/dev/vaultik/internal/cli/snapshot.go:71): ` +
+				`failed to build *vaultik.Vaultik: ` +
+				`could not build arguments for function ` +
+				`"sneak.berlin/go/vaultik/internal/vaultik".New ` +
+				`(/Users/user/dev/vaultik/internal/vaultik/vaultik.go:59): ` +
+				`failed to build storage.Storer: ` +
+				`received non-nil error from function ` +
+				`"sneak.berlin/go/vaultik/internal/storage".NewStorer ` +
+				`(/Users/user/dev/vaultik/internal/storage/module.go:23): ` +
+				`creating base path: mkdir /Volumes/BACKUPS: permission denied`,
 			want: `creating base path: mkdir /Volumes/BACKUPS: permission denied`,
 		},
 		{
@@ -30,6 +43,9 @@ func TestCleanStartupError(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			//nolint:err113 // test constructs errors from table input
 			got := cleanStartupError(errors.New(tt.in)).Error()
 			if got != tt.want {
 				t.Errorf("got %q, want %q", got, tt.want)