Enhance sample demo with animations, environment, VFX, and audio

**What**

Add presentation polish to the Unity package sample demo, including character/object animations, environment design, visual effects, and sound/audio cues.

**Why**

A polished sample demo is easier to evaluate, more representative of real game integration, and improves communication of OCR flows to developers and stakeholders.

**How**

* Add animations for key player and interaction moments in the sample flow
* Create or integrate a lightweight environment setup to improve scene readability and context
* Add visual effects for important OCR-driven events (for example access granted/denied, subscription success, or state transitions)
* Add audio cues/music/SFX to reinforce important interactions and outcomes
* Ensure added assets and effects do not break functional demo logic and remain performant in the sample scene
* Document required assets/setup and how to run the polished demo

**Acceptance Criteria**

* Sample demo includes visible animations for core interactions
* Scene has an environment that improves visual clarity and presentation
* VFX are present for key interaction outcomes and are triggered correctly
* Audio cues are integrated and mapped to relevant demo events
* Demo remains functional and performant with added presentation elements
* Documentation covers setup and usage of new visual/audio components

**Estimation**

**Dependencies**

None

Start with the Unity package sample demo and trace the existing OCR-driven interaction flow before planning presentation changes. Identify where core interactions and outcomes occur, then verify animations, environment elements, VFX, and audio are triggered correctly without breaking performance. Done means the acceptance criteria are met and the required asset setup and usage are documented.

Written by the indexing model from the issue text.