chore(yaml): enforce .yaml extension and prefer double quotes in YAML via eslint-plugin-yml; fix rule name; format repo

.github/workflows/discord.yaml

@@ -1,6 +1,6 @@
 name: Discord Notification
 
-on:
+"on":
   [
     pull_request,
     release,

.github/workflows/format-check.yaml

@@ -1,6 +1,6 @@
 name: format-check
 
-on:
+"on":
   pull_request:
     branches: ["**"]
 

.github/workflows/promote-to-stable.yaml

@@ -1,6 +1,6 @@
 name: Promote to Stable
 
-on:
+"on":
   workflow_dispatch:
     inputs:
       version_bump:

.github/workflows/release.yaml

@@ -23,7 +23,7 @@ permissions:
 jobs:
   release:
     runs-on: ubuntu-latest
-    if: "!contains(github.event.head_commit.message, '[skip ci]')"
+    if: '!contains(github.event.head_commit.message, "[skip ci]")'
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -34,8 +34,8 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: "20"
-          cache: npm
-          registry-url: https://registry.npmjs.org
+          cache: "npm"
+          registry-url: "https://registry.npmjs.org"
       - name: Install dependencies
         run: npm ci
       - name: Run tests and validation