chore(08-01): probe to manual-only (workflow_dispatch)

Stops the throwaway probe re-running on every push and contending with
ci.yml on the single runner. Fork answers already captured in 08-01-SUMMARY.

.gitea/workflows/runner-probe.yml

@@ -9,10 +9,11 @@ name: runner-probe
 # Checks performed: P-01 through P-11 + P-13
 # P-12 (docker login) is deferred to Plan 04 (publish) — DO NOT add it here.
 
+# Probe served its purpose (run #2 recorded the fork answers in 08-01-SUMMARY).
+# Switched to manual-only so it no longer re-runs on every push and competes
+# with ci.yml on the single runner. Throwaway — remove before merge to main.
 on:
-  push:
-    branches:
-      - gsd/phase-08-gitea-ci
+  workflow_dispatch:
 
 jobs:
   probe: