Chat tabs, chat mode, own modes, compaction notice, CLI binaries again

- Terminals and file managers as tabs of a chat; chat terminals keep running on
  the server (no idle timeout) and re-attach from any device
- "Just chat" in New session and a built-in chat mode with a lean prompt and only
  web tools; custom modes with kind (coding/conversation), read-only and tool picker
- Mode selector as a dropdown
- The chat shows running compactions (automatic: tokens and share of the limit)
  and labels summaries
- Docker image builds and serves the terminal client binaries again
- Fix: atomic session updates; background title/usage writes no longer undo each
  other (auto compaction triggered one turn late)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/store.rs

@@ -239,7 +239,7 @@ impl Store {
             if let Some(m) = mdata.and_then(|d| serde_json::from_str::<Message>(&d).ok()) {
                 for p in &m.parts {
                     let text = match p {
-                        Part::Text { text } | Part::Summary { text } | Part::Reasoning { text, .. } => text.as_str(),
+                        Part::Text { text } | Part::Summary { text, .. } | Part::Reasoning { text, .. } => text.as_str(),
                         Part::ToolResult { content, .. } => content.as_str(),
                         _ => continue,
                     };