[QA] Chat Reactions | No visual feedback when chat reactions are disabled - user unaware of OFF state

### 🛠️ Build version:
`v0.141.0-alpha-feat/chat-reactions-376d8a7`

### 📔 Issue Description:
When a user has the "See others' reactions" toggle set to OFF, there is no visual indicator in the chat interface to communicate this. The reactions area appears empty with no explanation, which can cause confusion — the user may assume reactions are broken or that no one is reacting, rather than understanding the feature is disabled on their end.

This is not a bug — the default setting is correctly ON in the current build. This is a UX improvement request to make the disabled state more visible and self-explanatory to the user.

### ✔️ Expected Result:
The chat reactions toggle should be set to ON by default for all users who have not explicitly changed the setting.

The toggle is ON in:
- the chat reactions bar next to the chat panel
- On settings -> Chat -> Chat Reactions

https://github.com/user-attachments/assets/37218ff5-57ba-43db-9095-6d4bb619a7d7

### ❌ Actual Result with evidence:
During the March 27 sync session, the setting was found to be OFF for at least one user with no recollection of having disabled it, suggesting the default may have been incorrectly set to OFF at some point during development.

I was unable to reproduce.

### 💡 Suggested Solutions:
The following are proposed approaches for Romina / design to evaluate:

1. Inline hint in the chat reactions area — when reactions are OFF, display a subtle label or icon in the reactions zone explaining why it appears empty, e.g. "Reactions are turned off" with a shortcut link to the setting.

2. Tooltip on the reactions button — when the toggle is OFF, hovering over the reactions button could surface a tooltip indicating the feature is disabled.

3. One-time dismissible notice — shown the first time a user enters a world after having disabled reactions, e.g. "You won't see others' reactions because this feature is turned off in your settings."

### 🔍 Background / Motivation:
During the March 27 sync session, Alvaro Luque was found to have chat reactions disabled in their settings without being aware of it.
This caused significant confusion during live testing, as reactions from other users were not visible and the root cause was not immediately obvious to anyone in the session. The team agreed at that time that the disabled state should be made more obvious to the user.

Verification on v0.141.0-alpha-feat/chat-reactions-376d8a7 with a fresh account confirmed the default is correctly set to ON on the current build. This ticket addresses the remaining discoverability gap.

#### 🖥️ Operative system and additional Notes:
- Suggested for @RominaMarchetti to assess and prioritize.
- Not blocking current release — recommended for a follow-up iteration.