Phase 0: skeleton, config, chi router, /healthz

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

internal/config/config.go

@@ -0,0 +1,53 @@
+package config
+
+import (
+	"os"
+	"strings"
+)
+
+type Config struct {
+	OpenAIAPIKey  string
+	SessionSecret string
+	DataDir       string
+	Port          string
+	AdminUsers    []AdminUser
+}
+
+type AdminUser struct {
+	Name     string
+	Password string
+}
+
+func Load() *Config {
+	cfg := &Config{
+		OpenAIAPIKey:  os.Getenv("OPENAI_API_KEY"),
+		SessionSecret: os.Getenv("SESSION_SECRET"),
+		DataDir:       envOr("DATA_DIR", "./data"),
+		Port:          envOr("PORT", "8080"),
+	}
+	cfg.AdminUsers = parseAdminUsers(os.Getenv("ADMIN_USERS"))
+	return cfg
+}
+
+func envOr(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}
+
+func parseAdminUsers(raw string) []AdminUser {
+	if raw == "" {
+		return nil
+	}
+	var users []AdminUser
+	for _, pair := range strings.Split(raw, ",") {
+		pair = strings.TrimSpace(pair)
+		name, pass, ok := strings.Cut(pair, ":")
+		if !ok || name == "" || pass == "" {
+			continue
+		}
+		users = append(users, AdminUser{Name: name, Password: pass})
+	}
+	return users
+}