ci: run verify_skills.py on every push and PR

Add .github/workflows/verify-skills.yml — installs pyyaml and runs
scripts/verify_skills.py on push and pull_request, failing the build if any skill
would not load. GitHub Actions runs it; Gitea Actions also reads .github/workflows/
when Actions is enabled, so it covers both remotes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/verify-skills.yml

@@ -0,0 +1,26 @@
+name: Verify Skills
+
+# Runs the skill load-verifier on every push and pull request.
+# Fails the build if any skill would not load (invalid frontmatter, bad name,
+# name collision, orphan dir, or invalid plugin.json). Read-only check.
+on:
+  push:
+  pull_request:
+
+jobs:
+  verify-skills:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install dependencies
+        run: pip install pyyaml
+
+      - name: Verify all skills load correctly
+        run: python3 scripts/verify_skills.py