Add outreach rejection reasons tab

docs/frontend.md

@@ -36,6 +36,8 @@ Prepared cards in the authenticated outreach funnel expose the exact opener, gro
 
 The funnel header also offers a destructive, confirmed **Clear funnel** action. Its dialog names the number of cancellable candidates, explains that audit rows remain and running discovery can refill the queue, and separately identifies any in-flight sends that cannot safely be cancelled. Success is reported from the authoritative API response before the funnel query refreshes.
 
+The outreach funnel separates the live queue from its terminal screening outcomes. Its **Rejections** tab groups durable rejected candidates by their recorded reason, so an empty queue can be diagnosed without exposing the rejected post content or treating a rejection as an operator action.
+
 Each non-sending candidate has a confirmed **Remove** action. Prepared candidates in ready or retrying state also have **Edit message**: the modal validates the 1–2000 character limit, the server re-applies outbound safeguards, and a successful edit is shown as operator-authored attribution. Buttons are intentionally absent once the candidate is sending, while the server still enforces the state boundary against stale pages.
 
 ## State model