feat: implement NFO ID storage and media scan tracking

Task 3 (NFO data):
- Add parse_nfo_ids() method to NFOService
- Extract TMDB/TVDB IDs from NFO files during scan
- Update database with extracted IDs
- Add comprehensive unit and integration tests

Task 4 (Media scan):
- Track initial media scan with SystemSettings flag
- Run background loading only on first startup
- Skip media scan on subsequent runs

src/server/fastapi_app.py

@@ -341,8 +341,52 @@ async def lifespan(_application: FastAPI):
                 await background_loader.start()
                 logger.info("Background loader service started")
                 
-                # Check for incomplete series and queue background loading
-                await _check_incomplete_series_on_startup(background_loader)
+                # Check if initial media scan has been completed
+                is_media_scan_done = False
+                try:
+                    async with get_db_session() as db:
+                        is_media_scan_done = (
+                            await SystemSettingsService
+                            .is_initial_media_scan_completed(db)
+                        )
+                except Exception as e:
+                    logger.warning(
+                        "Failed to check media scan status: %s, assuming not done",
+                        e
+                    )
+                    is_media_scan_done = False
+                
+                # Run media scan only on first run
+                if not is_media_scan_done:
+                    logger.info("Performing initial media scan...")
+                    try:
+                        # Check for incomplete series and queue background loading
+                        await _check_incomplete_series_on_startup(background_loader)
+                        logger.info("Initial media scan completed")
+                        
+                        # Mark media scan as completed
+                        try:
+                            async with get_db_session() as db:
+                                await (
+                                    SystemSettingsService
+                                    .mark_initial_media_scan_completed(db)
+                                )
+                            logger.info("Marked media scan as completed")
+                        except Exception as e:
+                            logger.warning(
+                                "Failed to mark media scan as completed: %s",
+                                e
+                            )
+                    except Exception as e:
+                        logger.error(
+                            "Failed to complete media scan: %s",
+                            e,
+                            exc_info=True
+                        )
+                else:
+                    logger.info(
+                        "Skipping media scan - already completed on previous run"
+                    )
             else:
                 logger.info(
                     "Download service initialization skipped - "