Add permissions to package-push workflow

Add contents:write and packages:read permissions to build-pkg job,
and contents:write to create-index job for release uploads.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: koki-develop

.github/workflows/package-push.yaml

@@ -13,6 +13,9 @@ jobs:
     build-pkg:
         name: Build package
         runs-on: ubuntu-latest
+        permissions:
+            contents: write
+            packages: read
         steps:
             - name: Checkout
               uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
@@ -49,6 +52,8 @@ jobs:
     create-index:
         name: Create Index
         runs-on: ubuntu-latest
+        permissions:
+            contents: write
         needs: build-pkg
         steps:
             - name: 'Download all release assets'