Chat, listings and feedback improvements

Community chat has more room on mobile, fewer messages are blocked by mistake, and you can now attach screenshots and videos to your feedback.

• Full-screen chat: Live chat now uses the full screen on mobile, and shared listings are more compact so they don't interrupt the conversation.
• Fewer chat restrictions: Some messages that were previously blocked now go through with a brief warning instead. Links to Roblox and Gameful work again.
• Usernames: More ordinary usernames are now accepted.
• Listings: Cards stay the same size however many items they contain, and item variants show their tags more clearly.
• Inventory: Pickers show all your items, not just the first 24, and search recognizes variant tags.
• Values: Large values display more accurately. For example, 1.95M no longer rounds to 2M.
• Feedback: Attach screenshots and videos when you send feedback, so you can show us exactly what you mean.