Address PR review feedback

- Add SHELL declaration to Makefile for bash compatibility
- Add check that release is run from main branch
- Use jq instead of grep -oP for JSON parsing in release.yml
- Move checkout before git ls-remote in create-release.yml
- Add --allow-empty to commit in create-release.yml

https://claude.ai/code/session_0158SxS2ATe6PL8zTpsoHRFn

.github/workflows/create-release.yml

@@ -23,6 +23,9 @@ jobs:
                     exit 1
                   fi
 
+            - name: Check out code
+              uses: actions/checkout@v5
+
             - name: Check tag does not already exist
               run: |
                   if git ls-remote --tags origin "refs/tags/v${{ inputs.version }}" | grep -q .; then
@@ -30,9 +33,6 @@ jobs:
                     exit 1
                   fi
 
-            - name: Check out code
-              uses: actions/checkout@v5
-
             - name: Set up Go
               uses: actions/setup-go@v5
               with:
@@ -49,6 +49,6 @@ jobs:
                   git config user.name "github-actions[bot]"
                   git config user.email "github-actions[bot]@users.noreply.github.com"
                   git add manifest.json
-                  git commit -m "Release v${{ inputs.version }}"
+                  git commit --allow-empty -m "Release v${{ inputs.version }}"
                   git tag "v${{ inputs.version }}"
                   git push origin main "v${{ inputs.version }}"