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.

client/src/lib/types.ts

@@ -2437,6 +2437,7 @@ export interface Lane {
   gate_decision: string | null;
   ci_status: string | null;
   needs_action: string | null;
+  needs_action_session?: string | null;
   links: Record<string, string>;
   stages: Record<string, { enteredAt: string; evidence: string | null; result: string | null }>;
   notes: string | null;