ci: drop the schedule triggers, race and fuzz run on dispatch alone

Assisted-by: GLM 5.3

.gitea/workflows/race.yml

@@ -1,20 +1,16 @@
-# Race, Go. Dispatched by hand and swept nightly on a schedule.
+# Race, Go. Dispatched by hand.
 #
 # The race detector roughly doubles both time and memory, which the shared runner box
 # cannot afford on every push. Locally it belongs to `just gates`, which runs it once
-# per task; here it is an explicit decision rather than a routine. The nightly
-# schedule runs on the repository's default branch, so it sweeps the released
-# line; development carries its race gate on every push through `just gates`
-# and the hand dispatch when a change asks for one.
+# per task; here it is an explicit decision rather than a routine, a hand dispatch
+# when a change asks for one. Development carries its race gate on every push through
+# that local gate.
 #
 # Every step is one command, so the step that fails is the gate that failed.
 name: Race
 
 on:
   workflow_dispatch:
-  schedule:
-    # Nightly at 03:00 UTC, the quietest hours of the shared box.
-    - cron: "0 3 * * *"
 
 env:
   # One core: parallelism buys no speed here and costs memory the box does not have.