Add admin config page and runtime-tunable upload/rate-limit settings

internal/web/handler.go

@@ -9,12 +9,21 @@ import (
 )
 
 type Handler struct {
-	fileService *file.Service
+	fileService   *file.Service
+	configService ConfigService
 }
 
-func NewHandler(fileService *file.Service) *Handler {
+// ConfigService is the small interface needed by the web layer.
+type ConfigService interface {
+	GetIntDefault(key string, def int) int
+	GetInt64Default(key string, def int64) int64
+	SetString(key, value string) error
+}
+
+func NewHandler(fileService *file.Service, cfg ConfigService) *Handler {
 	return &Handler{
-		fileService: fileService,
+		fileService:   fileService,
+		configService: cfg,
 	}
 }