feat: v2.6.0 — Chat UI composer (+ menu, project files, activity panel, permission mode, Stop), git on a workspace's extra folders (#70), long paste as a file (#68), S3 server mode (experimental)

Chat UI:
- Each Claude/Codex session keeps its own chat/terminal view; Settings only
  sets how new sessions open.
- Composer + menu: upload, project files and folders (#54, also dragged from
  the Files/Changes tree), context files, recent uploads, skills, plugins.
- Activity side panel (progress, outputs, files read, uploads, memory,
  skills, connectors) with a file preview; edited-file counts per turn.
- Permission-mode chip (Shift+Tab steps, read back from the pane:
  server/lib/pane-mode.js, GET|POST /api/run/:id/permission-mode).
- Stop (Esc) while the main agent works; the status is checked per agent
  (with session_id /api/agents ignores its status filter) and re-read every
  5 s while Stop shows.
- Dropped images shown in the conversation (GET /api/run/drop/:name, the
  requester's own drop dir), full-size viewer.
- A plain-text paste over 5,000 characters is attached as pasted-text.txt,
  so no prompt reaches tmux/argv limits (#68).

Changes panel: every /api/lanes/:id/git* route takes ?source=<lane_sources
id> (sourceFolder; ENOSOURCE otherwise) and a folder picker switches the
whole panel to a workspace's extra folder (#70).

Server mode S3 (one Linux user per account) — experimental, verified with
fake sudo plus a P6 managed-settings spike on a test account:
- member tmux listing runs in the background (cached, 15 s => unknown);
- transcript snapshot copy is async, chunked, temp file + rename;
- Express Layer patch only on Express 4;
- tmux capturePane/sendKey go to the member's own server.

Docs: the multi-user design moved in as docs/plans/server-mode/README.md
(the AgentHub-Server repo is gone); S3-PLAN P6 result; LANES/API/openapi.

client/src/components/run/LaneConsolePane.tsx

@@ -14,8 +14,9 @@
  * tab) attaches to that tmux session only; nothing is started or resumed.
  * A Claude or Codex pane also has a Chat view (`PaneChat`): the session's
  * conversation laid OVER the terminal, which stays mounted and attached under
- * it. Chat or terminal is the viewer's own Chat UI setting (Settings →
- * Appearance, `lib/chatUi.ts`, per account) — one choice for every pane.
+ * it. Chat or terminal is each SESSION's own (`useSessionChat`, the toggle
+ * left of the pane's split buttons); the Chat UI setting (Settings →
+ * Appearance, `lib/chatUi.ts`) is only what a session shows first.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
@@ -28,7 +29,7 @@ import type { Lane } from "../../lib/types";
 import { useAiTools } from "../../hooks/useAiTools";
 import { TerminalView } from "./TerminalView";
 import { PaneChat } from "./PaneChat";
-import { useChatUi } from "../../lib/chatUi";
+import { useSessionChat } from "../../lib/chatUi";
 
 const CHAT_TOOLS = new Set(["claude", "codex"]);
 
@@ -50,6 +51,8 @@ export interface LaneConsolePaneProps {
   onRunExit?: () => void;
   /** The terminal takes the keyboard when it appears (default). */
   autoFocus?: boolean;
+  /** The only pane shown: its Chat view gets the right panel. */
+  solo?: boolean;
 }
 
 /** The tmux session a lane's tab owns (see server/lib/pty-run.js). */
@@ -68,6 +71,7 @@ export function LaneConsolePane({
   onNewSession,
   onRunExit,
   autoFocus,
+  solo = false,
 }: LaneConsolePaneProps) {
   const { t } = useTranslation("run");
   const [handle, setHandle] = useState<RunHandle | null>(null);
@@ -78,11 +82,11 @@ export function LaneConsolePane({
   // The tool of the run on screen — a session's own, which need not be the
   // workspace's; the workspace's with no run.
   const paneTool = handle?.tool ?? currentLane?.tool ?? "claude";
-  const chat = useChatUi();
   // A run learns its session id after it starts (Codex): the page's poll has it.
   const chatSession = handle
     ? (activeRuns?.items.find((r) => r.id === handle.id)?.sessionId ?? handle.sessionId)
     : null;
+  const chat = useSessionChat(chatSession);
   const chatable = !!handle && !!chatSession && CHAT_TOOLS.has(handle.tool);
 
   useEffect(() => {
@@ -192,10 +196,12 @@ export function LaneConsolePane({
           {chatable && chat && (
             <div className="absolute inset-0 z-20 flex flex-col bg-surface-0">
               <PaneChat
-                runId={handle.id}
+                run={handle}
                 sessionId={chatSession}
-                tool={handle.tool}
                 cwd={handle.cwd || currentLane?.cwd || ""}
+                laneId={laneId}
+                laneCwd={currentLane?.cwd || ""}
+                outline={solo}
               />
             </div>
           )}