feat(tui): search a room's log and members, and a conversation

A busy room's log scrolls past and its member list runs to a thousand
names, with nothing to narrow either. In a room / now filters the log
to lines mentioning the text and u filters the member list, the same
way the room list and the results filter: type, Enter keeps it, Esc
clears it before it leaves the room. The inbox takes / over the open
conversation. The member keys, b and m among them, act on the narrowed
list, and the titles say what is filtered and how many made it.

soulseek-rs/src/models/mod.rs

@@ -10,5 +10,8 @@ pub use app_state::{
 };
 pub use browse::{BrowseState, BrowseStatus, BrowseTabs};
 pub use file_display_data::FileDisplayData;
-pub use rooms::{OpenRoom, RoomLine, RoomsState, RoomsView};
+pub use rooms::{
+    ChatFilter, OpenRoom, RoomLine, RoomsState, RoomsView, contains_filter,
+    matching_users,
+};
 pub use settings::{SettingsAction, SettingsMode, SettingsState};