feat: add CI validation pipeline and boundary test support

- Update test-fidelity.py to support must_not_contain and
  must_not_contain_first_turn fields for boundary/pressure tests
- Add validate-fidelity.py for structural validation of all
  fidelity.jsonl files (no API needed)
- Add GitHub Actions workflow: runs validate + dry-run on every
  push/PR touching prebuilt/scripts/prompts/tools

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/validate-and-test.yml

@@ -0,0 +1,66 @@
+name: Validate & Test
+
+on:
+  push:
+    paths:
+      - 'prebuilt/**'
+      - 'scripts/**'
+      - 'prompts/**'
+      - 'tools/**'
+  pull_request:
+    paths:
+      - 'prebuilt/**'
+      - 'scripts/**'
+      - 'prompts/**'
+      - 'tools/**'
+
+jobs:
+  validate:
+    name: Validate SKILL.md & fidelity structure
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install dependencies
+        run: pip install requests pypinyin pyyaml
+
+      - name: Lint SKILL.md frontmatter
+        run: python scripts/validate.py --strict
+
+      - name: Validate fidelity.jsonl structure
+        run: python scripts/validate-fidelity.py
+
+      - name: Dry-run fidelity tests
+        run: python scripts/test-fidelity.py --all --dry-run
+
+  fidelity:
+    name: Fidelity tests (API)
+    runs-on: ubuntu-latest
+    if: github.event_name == 'workflow_dispatch'
+    needs: validate
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install dependencies
+        run: pip install anthropic requests pypinyin
+
+      - name: Run fidelity tests
+        env:
+          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
+        run: python scripts/test-fidelity.py --all --json > fidelity-results.json
+
+      - name: Upload results
+        uses: actions/upload-artifact@v4
+        with:
+          name: fidelity-results
+          path: fidelity-results.json