refactor(main): delegate setup to config, store, and web packages

Replace in-file bootstrap logic with package-level constructors in `run`:
- use `config.Load()` instead of local env parsing/AppConfig helpers
- use `store.Open()` and `web.New()` for persistence and app wiring
- rename local store variable to `benchmarkStore` for clarity

This centralizes startup concerns in dedicated modules, reducing `main.go` boilerplate and improving maintainability.refactor(main): delegate setup to config, store, and web packages

Replace in-file bootstrap logic with package-level constructors in `run`:
- use `config.Load()` instead of local env parsing/AppConfig helpers
- use `store.Open()` and `web.New()` for persistence and app wiring
- rename local store variable to `benchmarkStore` for clarity

This centralizes startup concerns in dedicated modules, reducing `main.go` boilerplate and improving maintainability.

lib/config/config.go

@@ -0,0 +1,59 @@
+package config
+
+import (
+	"os"
+	"strconv"
+	"time"
+)
+
+type Config struct {
+	Addr            string
+	BadgerDir       string
+	PageSize        int
+	ShutdownTimeout time.Duration
+}
+
+func Load() Config {
+	return Config{
+		Addr:            envOrDefault("APP_ADDR", ":8080"),
+		BadgerDir:       envOrDefault("BADGER_DIR", "data/badger"),
+		PageSize:        envIntOrDefault("PAGE_SIZE", 50),
+		ShutdownTimeout: envDurationOrDefault("SHUTDOWN_TIMEOUT", 10*time.Second),
+	}
+}
+
+func envOrDefault(key, fallback string) string {
+	if value := os.Getenv(key); value != "" {
+		return value
+	}
+
+	return fallback
+}
+
+func envIntOrDefault(key string, fallback int) int {
+	value := os.Getenv(key)
+	if value == "" {
+		return fallback
+	}
+
+	parsed, err := strconv.Atoi(value)
+	if err != nil || parsed <= 0 {
+		return fallback
+	}
+
+	return parsed
+}
+
+func envDurationOrDefault(key string, fallback time.Duration) time.Duration {
+	value := os.Getenv(key)
+	if value == "" {
+		return fallback
+	}
+
+	parsed, err := time.ParseDuration(value)
+	if err != nil || parsed <= 0 {
+		return fallback
+	}
+
+	return parsed
+}