chore: Harden workflows: least-privilege permissions + zizmor integration (#1039)

* Harden workflows with least-privilege permissions and zizmor

Apply GitHub Actions security best practices to the action's own
workflows and integrate zizmor to catch regressions.

- Add explicit least-privilege `permissions:` to every workflow
  (contents: read for read-only workflows; default-deny `{}` with
  job-scoped grants for codeql, publish-immutable-actions and
  update-config-files).
- Set `persist-credentials: false` on all checkout steps that don't
  need the GITHUB_TOKEN afterwards.
- Move `${{ ... }}` expansions out of `run:` blocks into `env:` vars
  to avoid template injection.
- Pin the alpine container image (alpine:latest -> alpine:3.21).
- Add a zizmor CI workflow that uploads SARIF to code scanning, plus a
  `.github/zizmor.yml` pinning policy (ref-pin for actions/* and
  github/*, hash-pin for third-party actions).

zizmor now reports no findings (offline and online).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Fix indentation of if: in zizmor SARIF upload step

The `if:` key on the "Upload SARIF results to code scanning" step had no
indentation, producing invalid YAML ("Nested mappings are not allowed in
compact mappings"). This broke `npm run format-check` (prettier) in Basic
validation.

Indent `if:` to 8 spaces so it nests under the step alongside uses/with.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

.github/workflows/e2e-local-file.yml

@@ -11,6 +11,9 @@ on:
     paths-ignore:
       - '**.md'
 
+permissions:
+  contents: read
+
 jobs:
   setup-java-local-file-adopt:
     name: Validate installation from local file Adopt
@@ -22,6 +25,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v7
+        with:
+          persist-credentials: false
       - name: Download Adopt OpenJDK file
         run: |
           if ($IsLinux) {
@@ -46,7 +51,9 @@ jobs:
           java-version: '11.0.0-ea'
           architecture: x64
       - name: Verify Java version
-        run: bash __tests__/verify-java.sh "11.0.10" "${{ steps.setup-java.outputs.path }}"
+        env:
+          JAVA_PATH: ${{ steps.setup-java.outputs.path }}
+        run: bash __tests__/verify-java.sh "11.0.10" "$JAVA_PATH"
         shell: bash
 
   setup-java-local-file-zulu:
@@ -59,6 +66,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v7
+        with:
+          persist-credentials: false
       - name: Download Zulu OpenJDK file
         run: |
           if ($IsLinux) {
@@ -83,7 +92,9 @@ jobs:
           java-version: '11.0.0-ea'
           architecture: x64
       - name: Verify Java version
-        run: bash __tests__/verify-java.sh "11.0" "${{ steps.setup-java.outputs.path }}"
+        env:
+          JAVA_PATH: ${{ steps.setup-java.outputs.path }}
+        run: bash __tests__/verify-java.sh "11.0" "$JAVA_PATH"
         shell: bash
 
   setup-java-local-file-temurin:
@@ -96,6 +107,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v7
+        with:
+          persist-credentials: false
       - name: Download Eclipse Temurin file
         run: |
           if ($IsLinux) {
@@ -120,5 +133,7 @@ jobs:
           java-version: '11.0.0-ea'
           architecture: x64
       - name: Verify Java version
-        run: bash __tests__/verify-java.sh "11.0.12" "${{ steps.setup-java.outputs.path }}"
+        env:
+          JAVA_PATH: ${{ steps.setup-java.outputs.path }}
+        run: bash __tests__/verify-java.sh "11.0.12" "$JAVA_PATH"
         shell: bash