fix: v2.5.7 — panes work on psmux, the Windows tmux

psmux (the WinGet `tmux` on Windows) has no `=name` exact-match targets: it
answered "no server running on session '=agenthub-lane-1'" for a live pane,
so every Windows start reported "the session's command exited as soon as it
started" while the session ran on, and the browser could not attach.

- server/lib/tmux.js: `session`/`pane` targets probe the first live session
  once — `=name` failing where the bare name answers means bare names from
  then on; real tmux keeps `=name` / `=name:` (it matches by prefix otherwise)
- pty-attach.js and cc-update-all-helper.js use the same targets

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "agenthub",
-  "version": "2.5.6",
+  "version": "2.5.7",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "agenthub",
-      "version": "2.5.6",
+      "version": "2.5.7",
       "hasInstallScript": true,
       "license": "UNLICENSED",
       "dependencies": {