Add explicit permissions to workflow jobs for security

Co-authored-by: nirukk52 <[email protected]>

Author: Copilot

.github/workflows/ci.yml

@@ -15,6 +15,8 @@ jobs:
   lint:
     name: Lint
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
       - name: Checkout code
@@ -52,6 +54,8 @@ jobs:
   backend:
     name: Backend
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
       - name: Checkout code
@@ -78,6 +82,8 @@ jobs:
   frontend:
     name: Frontend
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
       - name: Checkout code
@@ -108,6 +114,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [lint, backend, frontend]
     if: always()
+    permissions: {}
 
     steps:
       - name: Check job results