Initial add backend stuff

config/config.go

@@ -0,0 +1,42 @@
+// Package config provides a generic environment-variable + .env configuration
+// loader. Each application defines its own configuration struct (with
+// `env:"..."` tags) and calls Load to populate it. The framework owns only the
+// loading mechanism, never the schema — so the two apps can have completely
+// different configuration structs while sharing this loader.
+package config
+
+import (
+	"os"
+
+	"github.com/caarlos0/env/v11"
+	"github.com/joho/godotenv"
+)
+
+// Load populates dst from the process environment. A ".env" file in the working
+// directory is loaded implicitly when present; passing a non-empty overrideFile
+// (e.g. from a --env-file flag) loads that file instead. In either case godotenv
+// never overwrites a variable already set in the real environment, so actual
+// environment variables always take precedence over the file.
+//
+// Load returns an error rather than exiting; callers (typically a thin app-side
+// wrapper) decide how to handle failure.
+func Load[T any](overrideFile string, dst *T) error {
+	switch {
+	case overrideFile != "":
+		// Explicit override: the file is required, so a missing/unreadable file
+		// is an error.
+		if err := godotenv.Load(overrideFile); err != nil {
+			return err
+		}
+	default:
+		// Implicitly load ".env" when it exists. Its absence is not an error —
+		// the process environment may already carry everything.
+		if _, err := os.Stat(".env"); err == nil {
+			if err := godotenv.Load(".env"); err != nil {
+				return err
+			}
+		}
+	}
+
+	return env.Parse(dst)
+}