Add YAML linter workflow for validating YAML schema (#6)

Author: dwydler

.github/FUNDING.yml

@@ -1 +1,2 @@
+---
 github: Cyclenerd

.github/ISSUE_TEMPLATE/config.yml

@@ -1,5 +1,6 @@
+---
 blank_issues_enabled: false
 contact_links:
   - name: Contact me on Mastodon
     url: https://fosstodon.org/@cyclenerd
-    about: Feel free to follow me on Mastodon and send me a message
+    about: Feel free to follow me on Mastodon and send me a message

.github/dependabot.yml

@@ -13,4 +13,4 @@ updates:
       interval: "weekly"
       day: "saturday"
       timezone: "Europe/Berlin"
-      time: "05:00"
+      time: "05:00"

.github/workflows/tools_codeql.yml

@@ -96,4 +96,4 @@ jobs:
       - name: Perform CodeQL Analysis
         uses: github/codeql-action/analyze@c10b8064de6f491fea524254123dbe5e09572f13  # v4.35.1
         with:
-          category: "/language:${{matrix.language}}"
+          category: "/language:${{matrix.language}}"

.github/workflows/tools_sync-fork-branch-master.yml

@@ -39,4 +39,4 @@ jobs:
           upstream_branch: master
           target_branch: master
           force: false
-          tags: false
+          tags: false

.github/workflows/tools_yaml_linter.yml

@@ -0,0 +1,30 @@
+---
+name: "Tools - Validate YAML Schema"
+
+"on":
+  pull_request:
+    branches:
+      - "customize"
+    paths:
+      - ".yamllint"
+      - "**.yaml"
+      - "**.yml"
+      - "**.yml.example"
+
+permissions:
+  contents: read
+
+jobs:
+  validate-yaml:
+    name: YAML Linter
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+
+      - name: Validate YAML files
+        run: yamllint .

.yamllint

@@ -0,0 +1,14 @@
+---
+extends: default
+
+yaml-files:
+  - '*.yaml'
+  - '*.yml'
+  - '.yamllint'
+  - '*.yml.example'
+
+rules:
+  empty-lines:
+    level: warning
+  line-length:
+    max: 255