Plane client, transports and executor adapters

Plane: paginated issue/comment/state/label/member access, one client per
terminal identity. Transports: local (setsid-detached runner) and warpgate-ssh
(win10-ps.sh / win10-put.sh relay, schtasks launch, taskkill on timeout).
Executors share a runner shape (prompt.md, exit.txt marker) with codex,
claude-code and shell adapters for last message and thread id.

agentd/executors/shell.py

@@ -0,0 +1,19 @@
+"""Shell/script executor: runs `{script}` with the prompt on stdin. The last message is `last.md` in the run
+directory if the script wrote it (its path is passed as {out}), else the tail of stdout. No threads."""
+from .base import ExecResult, RunnerExecutor
+
+
+class ShellExecutor(RunnerExecutor):
+    stdout_name = "stdout.txt"
+
+    @property
+    def resume(self):
+        return False
+
+    def collect(self, handle):
+        t, d = self.transport, handle["run_dir"]
+        last = t.read_text(t.join(d, "last.md"))
+        if last is None:
+            last = (t.read_text(t.join(d, "stdout.txt")) or "")[-6000:]
+        return ExecResult(last.strip(), self.exit_code(handle), None,
+                          self.logs(handle, "stdout.txt", "stderr.txt"), self.stderr_tail(handle))