Automatically prepare the bundled Navidrome sidecar and replace demo content with real-library scan states and polling

Hop-State: A_06FNEE4FJ502PSGDYQ3272G
Hop-Proposal: R_06FNED6AR1ZZM7CJH7ETC9G
Hop-Task: T_06FNEAPFW0DYEP35V3BMAHG
Hop-Attempt: AT_06FNEAPFW1QY3KAF1QM61N0

package.json

@@ -11,7 +11,7 @@
     "sidecar:prepare": "node scripts/prepare-navidrome.mjs",
     "desktop:dev": "npm run sidecar:prepare && tauri dev",
     "desktop:build": "npm run sidecar:prepare && tauri build",
-    "tauri": "tauri",
+    "tauri": "npm run sidecar:prepare && tauri",
     "check": "npm run sidecar:prepare && npm run test && npm run build && cargo check --manifest-path src-tauri/Cargo.toml"
   },
   "dependencies": {