fix: v2.5.6 — Windows panes without sh, UI build without node on PATH

- Windows panes: a WinGet tmux runs native programs and there is no `sh`, so
  every pane's `sh -c` wrapper died at once ("Command failed: tmux set-option
  … mouse on"). paneArgv runs the CLI itself on win32, and a Terminal gets
  tmux's own default shell (newSession drops the `--` for an empty argv).
- Plugin UI build: client deps install with --ignore-scripts and tsc/vite run
  by the running node instead of `npm run build`. On Windows esbuild's
  postinstall went through cmd.exe with no `node` on the server's PATH, both
  installs failed, and Update now kept the previous UI. A test keeps the two
  build steps equal to client/package.json's build script.
- Update all: Atomics.wait instead of a `sleep` binary Windows lacks.

server/lib/pty-run.js

@@ -77,6 +77,23 @@ const WAIT_FOR_CLIENT =
   'i=0; while [ "$(tmux display -p -t "$TMUX_PANE" \'#{session_attached}\' 2>/dev/null)" = 0 ]' +
   " && [ $i -lt 20 ]; do sleep 0.1; i=$((i+1)); done;";
 const CLIENT_WAIT_MS = 2000;
+
+/**
+ * A pane's tmux command: `argv` behind {@link WAIT_FOR_CLIENT}, or — with no
+ * `argv` — the login shell behind it. Windows has no `sh` (a WinGet tmux runs
+ * native programs), and an `sh -c` there died at once and took the session
+ * with it, so it gets the command itself, or nothing for tmux's own default
+ * shell.
+ * ponytail: no wait for the attach on Windows, so a pane may first draw at
+ * 80×24 (issue #55); port the wait to PowerShell if that shows.
+ */
+function paneArgv(argv, platform = process.platform) {
+  if (platform === "win32") return argv || [];
+  // argv rides as sh's positional parameters, never inside the script text.
+  return argv
+    ? ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$@"`, "sh", ...argv]
+    : ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$SHELL" -l`];
+}
 const CODEX_SANDBOXES = new Set(["read-only", "workspace-write", "danger-full-access"]);
 const CODEX_APPROVALS = new Set(["on-request", "never"]);
 // Codex has no `--effort` flag; reasoning effort is a config override.
@@ -493,13 +510,7 @@ function spawnRun(args) {
   };
 
   if (!tmux.hasSession(id)) {
-    // argv rides as sh's positional parameters, never inside the script text.
-    tmux.newSession({
-      name: id,
-      cwd,
-      argv: ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$@"`, "sh", ...argv],
-      env,
-    });
+    tmux.newSession({ name: id, cwd, argv: paneArgv(argv), env });
     record();
     schedulePaste();
   } else if (SHELL_COMMANDS.has(tmux.paneCommand(id) || "")) {
@@ -554,12 +565,7 @@ function spawnShell({ laneId, slot = 0, cwd }) {
   };
   // Started once the pane has its real size (WAIT_FOR_CLIENT, issue #55), as
   // the login shell tmux would have run (tmux sets SHELL in the pane).
-  tmux.newSession({
-    name: id,
-    cwd,
-    argv: ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$SHELL" -l`],
-    env,
-  });
+  tmux.newSession({ name: id, cwd, argv: paneArgv(null), env });
   dashboardRuns?.recordRun({
     id,
     sessionId: null,
@@ -636,4 +642,5 @@ module.exports = {
   runIdForLane,
   MAX_PANE_SLOT,
   SHELL_COMMANDS,
+  paneArgv,
 };