build: pin job container image to Gitea registry (v0)

Workflows now pull pi5-16.local:3005/mikkeli/novoyuuparosk-wiki-runner:v0
instead of relying on the host dockerd image cache. Registry is the
authority; act_runner pull_image flipped to true accordingly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/publish-ses.yml

@@ -10,7 +10,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     container:
-      image: novoyuuparosk-wiki-runner:latest
+      image: pi5-16.local:3005/mikkeli/novoyuuparosk-wiki-runner:v0
 
     steps:
       - name: Checkout ses-light-novel

.gitea/workflows/publish-songs.yml

@@ -19,7 +19,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     container:
-      image: novoyuuparosk-wiki-runner:latest
+      image: pi5-16.local:3005/mikkeli/novoyuuparosk-wiki-runner:v0
 
     steps:
       - name: Checkout ncmr-songs

.gitea/workflows/publish-tech.yml

@@ -10,7 +10,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     container:
-      image: novoyuuparosk-wiki-runner:latest
+      image: pi5-16.local:3005/mikkeli/novoyuuparosk-wiki-runner:v0
 
     steps:
       - name: Checkout tech-blogs