Add explicit GITHUB_TOKEN permissions to Docker workflow for security

Co-authored-by: npv2k1 <[email protected]>

Author: Copilot

.github/workflows/docker.yml

@@ -6,10 +6,15 @@ on:
   pull_request:
     branches: [ "main" ]
 
+permissions:
+  contents: read
+
 jobs:
   docker-build:
     name: Docker Build Test
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
     - uses: actions/checkout@v4
 
@@ -33,6 +38,8 @@ jobs:
   docker-compose:
     name: Docker Compose Validation
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
     - uses: actions/checkout@v4