Fix NFO API endpoint mismatch in frontend

- Update nfo-manager.js to use correct API routes:
  * POST /api/nfo/{id}/create (was /api/nfo/series/{id})
  * PUT /api/nfo/{id}/update (was /api/nfo/series/{id})
  * GET /api/nfo/{id}/content (was /api/nfo/series/{id})
- Add request body to createNFO with default options
- Fix response handling to check actual API fields
- Remove non-existent getStatistics function
- Fix getSeriesWithoutNFO response structure
- Update instructions.md with fix documentation

docs/instructions.md

@@ -109,3 +109,28 @@ For each task completed:
 ---
 
 ## TODO List:
+
+<!-- No pending issues -->
+
+## Recently Fixed Issues
+
+### 1. NFO API Endpoint Mismatch (Fixed: 2026-01-16)
+
+**Issue**: Frontend JavaScript was calling incorrect NFO API endpoints causing 404 errors.
+
+**Root Cause**: 
+- Frontend was using `/api/nfo/series/{key}` pattern
+- Backend API uses `/api/nfo/{serie_id}/create`, `/api/nfo/{serie_id}/update`, `/api/nfo/{serie_id}/content`
+
+**Changes Made**:
+- Updated [nfo-manager.js](../src/server/web/static/js/index/nfo-manager.js):
+  - Fixed `createNFO()`: Now calls `POST /api/nfo/{key}/create` with proper request body
+  - Fixed `refreshNFO()`: Now calls `PUT /api/nfo/{key}/update`
+  - Fixed `viewNFO()`: Now calls `GET /api/nfo/{key}/content`
+  - Updated response handling to check for actual API response fields (e.g., `message`, `content`)
+  - Removed non-existent `getStatistics()` function
+  - Fixed `getSeriesWithoutNFO()` to use correct endpoint and response structure
+
+**Status**: ✅ Fixed and tested
+
+---