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>

cmd/logpile/main.go

@@ -4,7 +4,7 @@ import (
 	"bufio"
 	"flag"
 	"fmt"
-	"log"
+	"log/slog"
 	"os"
 	"os/exec"
 	"runtime"
@@ -49,8 +49,8 @@ func main() {
 	srv := server.New(cfg)
 
 	url := fmt.Sprintf("http://localhost:%d", *port)
-	log.Printf("LOGPile starting on %s", url)
-	log.Printf("Registered parsers: %v", parser.ListParsers())
+	slog.Info("LOGPile starting", "url", url)
+	slog.Info("registered parsers", "parsers", parser.ListParsers())
 
 	// Open browser automatically
 	if !*noBrowser {
@@ -61,7 +61,7 @@ func main() {
 	}
 
 	if err := runServer(srv); err != nil {
-		log.Printf("FATAL: %v", err)
+		slog.Error("fatal error", "err", err)
 		maybeWaitForCrashInput(*holdOnCrash)
 		os.Exit(1)
 	}
@@ -90,7 +90,7 @@ func openBrowser(url string) {
 	}
 
 	if err := cmd.Start(); err != nil {
-		log.Printf("Failed to open browser: %v", err)
+		slog.Warn("failed to open browser", "err", err)
 	}
 }