Diagnose 3JSGames Storage

Diagnose this game's 3JSGames Storage integration without redesigning it.

Inspect and report:
- whether the exact official SDK exists at 3jsgames-sdk/v1/storage.js and is loaded from ./3jsgames-sdk/v1/storage.js;
- the result and timing of ThreeJSGames.storage.isAvailable();
- stable error.code values without parsing message strings;
- key validity against the documented key rule and 64-character maximum;
- whether values are JSON-compatible and each serialized payload is at most 32 KiB;
- whether the game is standalone or running inside 3JSGames;
- whether AUTH_REQUIRED indicates the player is not authenticated;
- whether key-count or total-quota limits are reached.

Do not replace the official SDK transport with direct window.parent access or custom postMessage communication. Do not connect to Supabase, invent identifiers, modify the SDK, or bypass the upload scanner.