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/lanes/WorkspaceRow.tsx

@@ -8,13 +8,14 @@
  * preference kept in localStorage (`laneOrderStorage.ts`), never written to
  * the lane row. The row only STARTS a drag (`LANE_DRAG_TYPE`); the list
  * (`WorkspaceTree.tsx`) takes the drop anywhere, gaps included. F2 renames too; the
- * dot's meaning is screen-reader text, and an idle dot is a ring.
+ * dot's meaning is screen-reader text, and an idle dot is a ring. A `readOnly`
+ * row (another user's workspace, for an analyst) has no menu, rename or `+`.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
 import { useState, type MouseEvent } from "react";
 import { useTranslation } from "react-i18next";
-import { ChevronDown, ChevronRight, MoreHorizontal, Plus } from "lucide-react";
+import { ChevronDown, ChevronRight, Eye, MoreHorizontal, Plus } from "lucide-react";
 import type { Lane } from "../../lib/types";
 import { isSubmitEnter } from "../../lib/keys";
 
@@ -49,6 +50,7 @@ export function workspaceName(lane: Lane): string {
 export function WorkspaceRow({
   lane,
   index,
+  readOnly,
   selected,
   expanded,
   renaming,
@@ -63,6 +65,9 @@ export function WorkspaceRow({
   lane: Lane;
   /** Position in the list — the unit both reorder paths speak in. */
   index: number;
+  /** Set (to its tooltip) for a workspace this user may only read: no menu,
+   *  no rename, no new session. */
+  readOnly?: string;
   selected: boolean;
   expanded: boolean;
   renaming: boolean;
@@ -82,7 +87,12 @@ export function WorkspaceRow({
   const openMenu = (e: MouseEvent) => {
     e.preventDefault();
     e.stopPropagation();
-    onMenu(e.clientX, e.clientY);
+    if (!readOnly) onMenu(e.clientX, e.clientY);
+  };
+  const startRename = () => {
+    if (readOnly) return;
+    setDraft(lane.title || "");
+    onRenameStart();
   };
   const Chevron = expanded ? ChevronDown : ChevronRight;
   const hoverBtn =
@@ -140,22 +150,18 @@ export function WorkspaceRow({
           aria-current={selected ? "true" : undefined}
           // A double-click's second click renames instead of opening again.
           onClick={(e) => e.detail < 2 && onSelect()}
-          onDoubleClick={() => {
-            setDraft(lane.title || "");
-            onRenameStart();
-          }}
+          onDoubleClick={startRename}
           onKeyDown={(e) => {
             if (e.key === "F2") {
               e.preventDefault();
-              setDraft(lane.title || "");
-              onRenameStart();
+              startRename();
               return;
             }
             if (!e.altKey || (e.key !== "ArrowUp" && e.key !== "ArrowDown")) return;
             e.preventDefault();
             onReorder(index, index + (e.key === "ArrowUp" ? -1 : 1));
           }}
-          title={`${lane.cwd}\n${t("row.hint")}`}
+          title={`${lane.cwd}\n${readOnly ?? t("row.hint")}`}
           className="flex min-w-0 flex-1 items-center gap-2 py-1.5 text-left"
         >
           <span aria-hidden className={`h-2 w-2 shrink-0 rounded-full ${workspaceDot(lane)}`} />
@@ -163,7 +169,8 @@ export function WorkspaceRow({
           <span className="truncate text-[13px] font-medium text-fg-primary">{name}</span>
         </button>
       )}
-      {!renaming && (
+      {readOnly && <Eye aria-label={readOnly} className="mr-1 h-3 w-3 shrink-0 text-fg-muted" />}
+      {!renaming && !readOnly && (
         <>
           <button
             type="button"