feat: allow individual ads to be manually triggered

README.md

@@ -75,10 +75,13 @@ edited from the dashboard and persists in NodeCG's database. Set
   speed) and message management; each active message shows a depleting fill
   for its remaining time, with renew/remove/inline-edit.
 - **Ads** — CRUD for ads (strip text, column text, column image from the
-  Assets dialog, QR URL, enabled), with a live QR preview per row.
+  Assets dialog, QR URL, enabled), with a live QR preview per row. Each row
+  has a "Trigger now" button to force that specific ad onto air immediately
+  (enabled or not), bypassing the round-robin — disabled while an ad slot is
+  already showing.
 - **Choreography / OBS** — connection status, mode/phase badges, countdown to
   the next automatic transition, break-slide content, and manual controls:
-  show ad now, skip ad, break toggle.
+  show ad now (round-robin), skip ad, break toggle.
 - **Timing** — the choreography timing settings: ad interval, ad duration,
   break gap, break ad duration, ads per burst.
 - **OBS setup check** — read-only verification of the live OBS against the