ci: declare workflow-level contents: read on 4 workflows

Pins the default GITHUB_TOKEN to contents: read on the workflows in
.github/workflows/ that don't call a GitHub API beyond the initial
checkout. The other workflows in this directory are left implicit
because they need write scopes that a maintainer is better placed
to declare.

Motivation: CVE-2025-30066 (March 2025 tj-actions/changed-files
compromise) exfiltrated GITHUB_TOKEN from workflow logs. Per-workflow
caps bound runtime authority irrespective of repo or org default,
give drift protection if the default ever widens, and are credited
per-file by the OpenSSF Scorecard Token-Permissions check.

YAML validated locally with yaml.safe_load.

Signed-off-by: Arpit Jain <[email protected]>

Author: arpitjain099

.github/workflows/validate-js-functions.yml

@@ -11,6 +11,9 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
+permissions:
+  contents: read
+
 jobs:
   checks:
     runs-on: ubuntu-latest

.github/workflows/validate-rust-functions.yml

@@ -13,6 +13,9 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
+permissions:
+  contents: read
+
 jobs:
   checks:
     runs-on: ubuntu-latest

.github/workflows/validate-ts-functions.yml

@@ -11,6 +11,9 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
+permissions:
+  contents: read
+
 jobs:
   checks:
     runs-on: ubuntu-latest

.github/workflows/validate-wasm-functions.yml

@@ -11,6 +11,9 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
+permissions:
+  contents: read
+
 jobs:
   checks:
     runs-on: ubuntu-latest