feat: add config package with env-var loading

internal/config/config.go

@@ -0,0 +1,29 @@
+package config
+
+import "os"
+
+type Config struct {
+	Port           string // SUPERVISOR_PORT, default 3200
+	LiteLLMBaseURL string // LITELLM_BASE_URL, default http://iguana:4000
+	LiteLLMAPIKey  string // LITELLM_API_KEY
+	ConfigDir      string // SUPERVISOR_CONFIG_DIR, default ./config/supervisor
+	ModelsFile     string // SUPERVISOR_MODELS_FILE, default <ConfigDir>/../models.yaml
+}
+
+func Load() (Config, error) {
+	cfg := Config{
+		Port:           envOr("SUPERVISOR_PORT", "3200"),
+		LiteLLMBaseURL: envOr("LITELLM_BASE_URL", "http://iguana:4000"),
+		LiteLLMAPIKey:  os.Getenv("LITELLM_API_KEY"),
+		ConfigDir:      envOr("SUPERVISOR_CONFIG_DIR", "./config/supervisor"),
+	}
+	cfg.ModelsFile = envOr("SUPERVISOR_MODELS_FILE", cfg.ConfigDir+"/../models.yaml")
+	return cfg, nil
+}
+
+func envOr(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}