chore: align codebase with bible engineering contracts

- identifier-normalization: use strings.EqualFold in h3c/parser.go
- import-export: CSV now uses UTF-8 BOM and semicolon delimiter
- go-code-style: translate all Russian source strings to English (ADL-007)
- go-background-tasks: add Type, Message, Result fields to Job struct
- go-api: wrap list endpoints in {items, total_count, page, per_page, total_pages}
- module-structure: rename helpers.go → context_sleep.go
- build-version-display: htmlError renders version footer on error pages
- go-logging: migrate all log.Printf calls to log/slog with structured attrs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/collector/context_sleep.go

@@ -0,0 +1,18 @@
+package collector
+
+import (
+	"context"
+	"time"
+)
+
+func sleepWithContext(ctx context.Context, d time.Duration) bool {
+	timer := time.NewTimer(d)
+	defer timer.Stop()
+
+	select {
+	case <-ctx.Done():
+		return false
+	case <-timer.C:
+		return true
+	}
+}