chore: Harden GitHub Actions workflow permissions

Add explicit permissions and persist-credentials: false to all workflows.

Without an explicit permissions block, GITHUB_TOKEN inherits the repo default (write-all). These CI workflows only need contents: read. The release workflow already declares contents: write at job level where needed.

persist-credentials: false prevents the token from lingering in .git/config for subsequent steps, reducing attack surface if a third-party action is compromised.

.github/workflows/code-checks.yml

@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+permissions:
+  contents: read
+
 jobs:
   lint-vital:
     name: Lint vitals
@@ -19,6 +22,8 @@ jobs:
     steps:
       - name: Checkout source code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd #v6.0.2
+        with:
+          persist-credentials: false
       - name: Setup project and build environment
         uses: ./.github/actions/common-setup
 
@@ -37,6 +42,8 @@ jobs:
     steps:
       - name: Checkout source code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd #v6.0.2
+        with:
+          persist-credentials: false
       - name: Setup project and build environment
         uses: ./.github/actions/common-setup
 
@@ -54,6 +61,8 @@ jobs:
     steps:
       - name: Checkout source code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd #v6.0.2
+        with:
+          persist-credentials: false
       - name: Setup project and build environment
         uses: ./.github/actions/common-setup
 
@@ -66,5 +75,7 @@ jobs:
     steps:
       - name: Checkout source code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd #v6.0.2
+        with:
+          persist-credentials: false
       - name: Validate metadata lengths
         run: bash fastlane/check_metadata_length.sh