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>

web/src/store.ts

@@ -47,6 +47,8 @@ export interface State {
   queue: Record<string, QueueItem[]>;
   /** Why a session waits: "model:<spec>" or "subagent:<name>". */
   waiting: Record<string, string | undefined>;
+  /** Compaction running in a session (auto = context nearly full). */
+  compacting: Record<string, { auto: boolean; tokens: number | null; limit: number | null; since: number } | undefined>;
 }
 
 let state: State = {
@@ -67,6 +69,7 @@ let state: State = {
   queue: {},
   steps: {},
   waiting: {},
+  compacting: {},
 };
 
 const listeners = new Set<() => void>();
@@ -188,6 +191,14 @@ export function applyEvent(ev: ServerEvent) {
     case "waiting":
       setState((s) => ({ waiting: { ...s.waiting, [ev.session_id]: ev.reason ?? undefined } }));
       break;
+    case "compaction":
+      setState((s) => ({
+        compacting: {
+          ...s.compacting,
+          [ev.session_id]: ev.state === "started" ? { auto: ev.auto, tokens: ev.tokens, limit: ev.limit, since: Date.now() } : undefined,
+        },
+      }));
+      break;
     case "mcp_status":
       setState(() => ({ mcp: ev.servers }));
       break;