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/globals/globals.go

@@ -1,3 +1,5 @@
+// Package globals holds application-wide metadata (name, version,
+// commit) that is populated at build time via linker flags.
 package globals
 
 import (
@@ -5,16 +7,16 @@ import (
 )
 
 // Appname is the application name, populated from main().
-var Appname string = "vaultik"
+var Appname = "vaultik" //nolint:gochecknoglobals // set via -ldflags at build time
 
 // Version is the application version, populated from main().
-var Version string = "dev"
+var Version = "dev" //nolint:gochecknoglobals // set via -ldflags at build time
 
 // Commit is the git commit hash, populated from main().
-var Commit string = "unknown"
+var Commit = "unknown" //nolint:gochecknoglobals // set via -ldflags at build time
 
 // CommitDate is the ISO-8601 date of the commit, populated from main().
-var CommitDate string = "unknown"
+var CommitDate = "unknown" //nolint:gochecknoglobals // set via -ldflags at build time
 
 // Author identifies the upstream author of vaultik.
 const Author = "Jeffrey Paul <sneak@sneak.berlin>"
@@ -34,7 +36,8 @@ type Globals struct {
 	StartTime  time.Time
 }
 
-// New creates and returns a new Globals instance initialized with the package-level variables.
+// New creates and returns a new Globals instance initialized with the
+// package-level variables.
 func New() (*Globals, error) {
 	return &Globals{
 		Appname:    Appname,
@@ -44,11 +47,14 @@ func New() (*Globals, error) {
 	}, nil
 }
 
+// shortCommitLen is the number of commit-hash characters ShortCommit keeps.
+const shortCommitLen = 12
+
 // ShortCommit returns the first 12 chars of the commit hash, or the
 // whole string if it's shorter (e.g. "unknown").
 func (g *Globals) ShortCommit() string {
-	if len(g.Commit) > 12 {
-		return g.Commit[:12]
+	if len(g.Commit) > shortCommitLen {
+		return g.Commit[:shortCommitLen]
 	}
 
 	return g.Commit

internal/globals/globals_test.go

@@ -1,12 +1,16 @@
-package globals
+package globals_test
 
 import (
 	"testing"
+
+	"sneak.berlin/go/vaultik/internal/globals"
 )
 
 // TestGlobalsNew ensures the globals package initializes correctly
 func TestGlobalsNew(t *testing.T) {
-	g, err := New()
+	t.Parallel()
+
+	g, err := globals.New()
 	if err != nil {
 		t.Fatalf("Failed to create Globals: %v", err)
 	}