fix(config): Fix environment variable mapping for Docker

- Add SetEnvKeyReplacer to convert underscores to dots
- Explicitly bind DATABASE_DSN, REGISTRY_CONSUL_ADDRESS, REGISTRY_TYPE
- Fixes database connection issues in Docker where services couldn't
  read DATABASE_DSN environment variable
- Services in Docker can now connect to postgres:5432 instead of localhost

internal/config/config.go

@@ -3,6 +3,7 @@ package config
 
 import (
 	"fmt"
+	"strings"
 	"time"
 
 	"git.dcentral.systems/toolz/goplt/pkg/config"
@@ -95,9 +96,13 @@ func LoadConfig(env string) (config.ConfigProvider, error) {
 
 	// Enable environment variable support
 	v.AutomaticEnv()
-	// Environment variables can be set in UPPER_SNAKE_CASE format
-	// and will automatically map to nested keys (e.g., SERVER_PORT -> server.port)
-	// Viper handles this automatically with AutomaticEnv()
+	// Set env key replacer to convert UPPER_SNAKE_CASE to nested keys
+	// e.g., DATABASE_DSN -> database.dsn, SERVER_PORT -> server.port
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	// Bind specific environment variables to config keys
+	v.BindEnv("database.dsn", "DATABASE_DSN")
+	v.BindEnv("registry.consul.address", "REGISTRY_CONSUL_ADDRESS")
+	v.BindEnv("registry.type", "REGISTRY_TYPE")
 
 	return NewViperConfig(v), nil
 }