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/config/size.go

@@ -3,13 +3,21 @@ package config
 import (
 	"errors"
 	"fmt"
+	"math"
 
 	"github.com/dustin/go-humanize"
 )
 
+var (
+	errSizeType     = errors.New("size must be a number or string")
+	errSizeTooLarge = errors.New("size exceeds maximum supported value")
+)
+
 // Size represents a byte size that can be specified in configuration files.
 // It can unmarshal from both numeric values (interpreted as bytes) and
 // human-readable strings like "10MB", "2.5GB", or "1TB".
+//
+//nolint:recvcheck // UnmarshalYAML requires a pointer; String/Int64 are value reads
 type Size int64
 
 // UnmarshalYAML implements yaml.Unmarshaler for Size, allowing it to be
@@ -31,7 +39,7 @@ func (s *Size) UnmarshalYAML(unmarshal func(any) error) error {
 
 	err = unmarshal(&strVal)
 	if err != nil {
-		return errors.New("size must be a number or string")
+		return errSizeType
 	}
 
 	// Parse the string using go-humanize
@@ -40,6 +48,10 @@ func (s *Size) UnmarshalYAML(unmarshal func(any) error) error {
 		return fmt.Errorf("invalid size format: %w", err)
 	}
 
+	if bytes > math.MaxInt64 {
+		return fmt.Errorf("%w: %s", errSizeTooLarge, strVal)
+	}
+
 	*s = Size(bytes)
 
 	return nil
@@ -56,6 +68,7 @@ func (s Size) Int64() int64 {
 // For example, 1048576 bytes would be formatted as "1.0 MB".
 // This implements the fmt.Stringer interface.
 func (s Size) String() string {
+	//nolint:gosec // G115: sizes are non-negative by construction
 	return humanize.Bytes(uint64(s))
 }
 
@@ -66,5 +79,9 @@ func ParseSize(s string) (Size, error) {
 		return 0, fmt.Errorf("invalid size format: %w", err)
 	}
 
+	if bytes > math.MaxInt64 {
+		return 0, fmt.Errorf("%w: %s", errSizeTooLarge, s)
+	}
+
 	return Size(bytes), nil
 }