add packages:write permission to CI workflows

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/docker-build.yml

@@ -4,6 +4,10 @@ on:
   push:
     branches:
       - "main"
+permissions:
+  packages: write
+  contents: read
+
 jobs:
   builder:
     name: 🏗️ Docker builder (latest from master) 🏗️

.gitea/workflows/docker-tag.yml

@@ -4,6 +4,10 @@ on:
   push:
     tags:
       - "v*"
+permissions:
+  packages: write
+  contents: read
+
 jobs:
   builder:
     name: 🏗️ Docker builder release tag 🏗️