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/storage/rclone.go

@@ -69,7 +69,8 @@ func (r *RcloneStorer) Put(ctx context.Context, key string, data io.Reader) erro
 	}
 
 	// Upload the object
-	_, err = operations.Rcat(ctx, r.fsys, key, io.NopCloser(bytes.NewReader(buf)), time.Now(), nil)
+	_, err = operations.Rcat(ctx, r.fsys, key,
+		io.NopCloser(bytes.NewReader(buf)), time.Now(), nil)
 	if err != nil {
 		return fmt.Errorf("uploading object: %w", err)
 	}
@@ -78,7 +79,10 @@ func (r *RcloneStorer) Put(ctx context.Context, key string, data io.Reader) erro
 }
 
 // PutWithProgress stores data with progress reporting.
-func (r *RcloneStorer) PutWithProgress(ctx context.Context, key string, data io.Reader, size int64, progress ProgressCallback) error {
+func (r *RcloneStorer) PutWithProgress(
+	ctx context.Context, key string, data io.Reader,
+	_ int64, progress ProgressCallback,
+) error {
 	// Wrap reader with progress tracking
 	pr := &progressReader{
 		reader:   data,
@@ -181,7 +185,9 @@ func (r *RcloneStorer) List(ctx context.Context, prefix string) ([]string, error
 }
 
 // ListStream returns a channel of ObjectInfo for large result sets.
-func (r *RcloneStorer) ListStream(ctx context.Context, prefix string) <-chan ObjectInfo {
+func (r *RcloneStorer) ListStream(
+	ctx context.Context, prefix string,
+) <-chan ObjectInfo {
 	ch := make(chan ObjectInfo)
 
 	go func() {
@@ -212,14 +218,14 @@ func (r *RcloneStorer) ListStream(ctx context.Context, prefix string) <-chan Obj
 }
 
 // Info returns human-readable storage location information.
-func (r *RcloneStorer) Info() StorageInfo {
+func (r *RcloneStorer) Info() Info {
 	location := r.remote
 	if r.path != "" {
 		location += ":" + r.path
 	}
 
-	return StorageInfo{
-		Type:     "rclone",
+	return Info{
+		Type:     schemeRclone,
 		Location: location,
 	}
 }