feat: add photo cap per event and Portuguese (pt-BR) locale

- Add photo_cap column to events table (migration 074) to limit photos per event
- Enforce photo cap in upload route, returning 400 when limit exceeded
- Pass photo_cap through all event CRUD routes and frontend forms
- Add complete Portuguese (pt-BR) translation (2300+ strings)
- Register pt locale in i18n config, language selector, date formatting
- Add photoCap/photoCapHelp translation keys to all locale files (en, de, ru, pt)

frontend/src/types/index.ts

@@ -53,6 +53,8 @@ export interface Event {
   hero_image_anchor?: string;
   // CSS Template
   css_template_id?: number | null;
+  // Photo cap
+  photo_cap?: number | null;
 }
 
 export interface GalleryInfo {
@@ -202,6 +204,7 @@ export interface GalleryAuthResponse {
     allow_user_uploads?: boolean;
     upload_category_id?: number | null;
     require_password?: boolean;
+    photo_cap?: number | null;
   };
 }