fix: v2.6.2 — Windows panes no longer read as dead (psmux ignores -F), Update now's setup works under cmd.exe

- psmux prints `name: 1 windows (created …)` whatever `list-sessions -F`
  asks for. Read as names, every live pane looked gone and the heal beat
  closed its run (and its tab) within seconds while the session kept
  running. tmux.js (and the Update all helper) now take the text before the
  first `:` — a session name never holds one.
- `npm run setup` used `(cd client && npm install)`; cmd.exe's ( ) is no
  subshell, so `npm run link-cli` ran inside client/ ("Missing script") and
  Update now failed on Windows. Now `npm --prefix client install`.
- Update now: an npm step names itself in its error and shows the END of
  npm's output (the error, not the warnings), says when it hit the time
  limit, and gets 20 min instead of 5.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "agenthub",
-  "version": "2.6.1",
+  "version": "2.6.2",
   "bin": {
     "agenthub": "bin/agenthub.js"
   },
@@ -55,7 +55,7 @@
     "dev:client": "cd client && npm run dev",
     "build": "cd client && npm run build",
     "start": "node server/index.js",
-    "setup": "npm install && (cd client && npm install) && npm run link-cli",
+    "setup": "npm install && npm --prefix client install && npm run link-cli",
     "update:pull-setup": "git pull --ff-only && npm run setup",
     "install-hooks": "node scripts/install-hooks.js",
     "seed": "node scripts/seed.js",