fix(tmux,run,hooks): the four pre-existing bugs the #37 evaluation found

- tmux targets are exact (`=name`, `=name:` for panes/options): a bare
  `-t agenthub-lane-1` resolves by prefix to agenthub-lane-12 once lane 1
  is gone, so killing a finished lane could kill another.
- getRun/killRun refuse ids that are not `agenthub-lane-<n>`, so
  DELETE /api/run/main can no longer kill a user's own tmux session.
- router/apply reports restart_required only for a running pane; getRun
  returns a `gone` handle, so it was always true.
- needs_action is cleared only by the session that raised it (new nullable
  lanes.needs_action_session); a second session in the same cwd used to
  clear it on its second hook.

server/lib/pty-run.js

@@ -322,8 +322,10 @@ function spawnRun(args) {
   return getRun(id);
 }
 
+// Only a dashboard lane pane is a run. Without this, `DELETE /api/run/main`
+// would kill the user's own tmux session named `main`.
 function killRun(id) {
-  if (!id || !tmux.hasSession(id)) return false;
+  if (laneIdFromRunId(id) === null || !tmux.hasSession(id)) return false;
   tmux.killSession(id);
   if (dashboardRuns) {
     dashboardRuns.patchRun({ id, status: "killed", endedAt: Date.now() });
@@ -353,7 +355,7 @@ function publicRun(id) {
 }
 
 function getRun(id) {
-  if (!id) return null;
+  if (laneIdFromRunId(id) === null) return null;
   return publicRun(id);
 }