Update golangci-lint to v2.12.2 with canonical config (#62)

Updates golangci-lint to v2.12.2 everywhere it is pinned and installs the canonical `.golangci.yml`, then remediates every finding the new linter/config surfaces so `make check` is green.

## Version bump

- `Dockerfile` lint stage: `golangci/golangci-lint:v2.11.3-alpine` -> `v2.12.2-alpine` (digest-pinned, date comment updated)
- `Makefile` `deps` target: `go install` moved from the old v1 module path at `@latest` to the pinned `github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2`
- `.golangci.yml` replaced with the canonical config (v2 schema; settings under `linters.settings` so the thresholds actually apply; `default: all` with the standard six disables)
- `script/bootstrap` installs golangci-lint via the system package manager and carries no version pin, so it is unchanged
- CI (`.gitea/workflows/check.yml`) only runs `script/cibuild`, so it needed no change

## Lint remediation

The canonical config surfaced ~3,300 findings across 56k lines. All are fixed, behavior-preserving; incorporates and supersedes the per-package mechanical passes already merged to `main` (refs #61). Highlights:

- `err113`: dynamic errors replaced with package sentinels + `%w` wrapping; comparisons via `errors.Is`
- `goprintffuncname`: printf-style helpers renamed with an `f` suffix (`ui.Writer` message methods, `cli.ReportErrorf`, `database.Fatalf`) and all call sites updated
- `revive` stutter renames: `blob.Handler`, `blob.WithReader`, `blob.ChunkPosition`, `storage.URL`, `storage.Info`; missing doc comments added
- `contextcheck`/`noctx`: `context.Context` threaded through `blob.Packer` and the scanner call sites; context-aware `exec`/`sql` variants
- `funlen`/`cyclop`/`gocognit`/`dupl`: oversized and duplicated functions split into focused helpers (production and test code)
- tests: `t.Parallel()` added where safe (global logger init kept in the serial phase for `-race`), `t.TempDir()`/`t.Helper()` adopted, several suites converted to external test packages
- `gosec`: bounded integer conversions, `ReadHeaderTimeout` on the test HTTP server; remaining warnings suppressed per-site with justifications
- remaining `nolint` directives are rare, targeted, and each carries a reason (e.g. `nilnil` not-found contract in the repository layer, fx module globals, on-disk snake_case struct tags)
- removed the deprecated `log.LogOptions` alias (callers migrated to `log.Options`)

`make check` (tests with `-race`, lint, fmt-check) passes.

Co-authored-by: sneak <sneak@sneak.berlin>
Reviewed-on: #62
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

internal/cli/version.go

@@ -2,6 +2,7 @@ package cli
 
 import (
 	"fmt"
+	"os"
 	"runtime"
 
 	"github.com/spf13/cobra"
@@ -15,21 +16,25 @@ func NewVersionCommand() *cobra.Command {
 		Short: "Print version information",
 		Long:  `Print version, git commit, and build information for vaultik.`,
 		Args:  cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			fmt.Printf("vaultik %s\n", globals.Version)
-			fmt.Printf("  commit:     %s\n", globals.Commit)
-			fmt.Printf("  build date: %s\n", globals.CommitDate)
-			fmt.Printf("  go:         %s\n", runtime.Version())
-			fmt.Printf("  os/arch:    %s/%s\n", runtime.GOOS, runtime.GOARCH)
-			fmt.Printf("  author:     %s\n", globals.Author)
-			fmt.Printf("  homepage:   %s\n", globals.Homepage)
-			fmt.Printf("  license:    %s\n", globals.License)
+		Run: func(_ *cobra.Command, _ []string) {
+			_, _ = fmt.Fprintf(os.Stdout, "vaultik %s\n", globals.Version)
+			_, _ = fmt.Fprintf(os.Stdout, "  commit:     %s\n", globals.Commit)
+			_, _ = fmt.Fprintf(os.Stdout, "  build date: %s\n", globals.CommitDate)
+			_, _ = fmt.Fprintf(os.Stdout, "  go:         %s\n", runtime.Version())
+			_, _ = fmt.Fprintf(os.Stdout, "  os/arch:    %s/%s\n",
+				runtime.GOOS, runtime.GOARCH)
+			_, _ = fmt.Fprintf(os.Stdout, "  author:     %s\n", globals.Author)
+			_, _ = fmt.Fprintf(os.Stdout, "  homepage:   %s\n", globals.Homepage)
+			_, _ = fmt.Fprintf(os.Stdout, "  license:    %s\n", globals.License)
 
 			if globals.Version == "dev" {
-				fmt.Println()
-				fmt.Println("This is a development build (no version information embedded).")
-				fmt.Println("Build a release binary with 'make vaultik' or download from")
-				fmt.Println("https://sneak.berlin/go/vaultik for embedded version metadata.")
+				_, _ = fmt.Fprintln(os.Stdout)
+				_, _ = fmt.Fprintln(os.Stdout,
+					"This is a development build (no version information embedded).")
+				_, _ = fmt.Fprintln(os.Stdout,
+					"Build a release binary with 'make vaultik' or download from")
+				_, _ = fmt.Fprintln(os.Stdout,
+					"https://sneak.berlin/go/vaultik for embedded version metadata.")
 			}
 		},
 	}