T23b: AI chat, citations

- CitationBadge: a numbered pill after a claim, its source on hover, a press
  opens it; a Tab stop
- SourceCard and SourceList: the sources folded under their count and sites,
  each a card numbered as cited; the fold opens from the keyboard
- SearchProgress: steps waiting, working and done
- WebResultCard and DocumentChunkPreview with matched words washed
- gallery: citation and sources states

src/chat/mod.rs

@@ -1,9 +1,11 @@
 mod actions;
+mod cite;
 mod code;
 mod list;
 mod media;
 mod message;
 mod play;
+mod search;
 mod status;
 mod stream;
 #[cfg(all(test, feature = "test-support"))]
@@ -13,6 +15,7 @@ pub use actions::{
     BranchNavigator, MessageActions, MessageEditor, QuoteReply, continue_button, regenerate_button,
     stop_button,
 };
+pub use cite::{CitationBadge, Source, SourceCard, SourceList};
 pub use code::CodeBlock;
 pub use list::{DateSeparator, MessageList, ScrollToBottomButton};
 pub use media::{FileMessage, ImageGrid, ImageMessage, LinkPreviewCard};
@@ -20,6 +23,7 @@ pub use message::{
     ChatContainer, MessageAvatar, MessageBubble, MessageFooter, MessageHeader, Role,
 };
 pub use play::{AudioMessage, VideoMessage};
+pub use search::{DocumentChunkPreview, SearchProgress, StepState, WebResultCard};
 pub use status::{
     ErrorMessage, FeedbackForm, RateLimitNotice, ThinkingBlock, ThinkingDuration, ThinkingIndicator,
 };