feat: in-chat search and reply-click-to-scroll in group rooms

[barrydeen]

Summary

• Adds a search icon to the group chat room top bar that opens a search field below the avatar strip
• Typing a keyword and pressing search finds all case-insensitive matches in visible messages, scrolls to the oldest match, and applies a breathing blink highlight
• Shows a match counter (e.g. 1/5) with up/down arrows to navigate between results
• Tapping a reply quote block now scrolls to and highlights the original message (auto-dismisses after 3s)

Test plan

• Open a group chat room and tap the search icon — verify the search bar appears with auto-focus
• Type a keyword and press search on the keyboard — verify it scrolls to the oldest match with blink highlight
• Use up/down arrows to navigate between matches — verify counter updates and highlight moves
• Close search (X icon) — verify highlight clears and search bar dismisses
• Tap a reply quote block on a message — verify it scrolls to and highlights the original message, then fades after 3s
• Verify no jank while typing in the search field (search only runs on enter)