feat(P18): testing + CI/CD pipelines - pytest suite, check-only mode, Gitea + GitHub workflows (v1.3.2)

90 offline tests covering adapter, confidence_signal, checkov_adapter,
outbox_writer, and pipeline integration. Identical CI/CD workflows for
Gitea Actions (dev) and GitHub Actions (production). New --check-only
mode for run_platform.sh (offline, no AWS).

---ci---
project: acdl
phase: 18
milestone: v1.3
status: verify
---/ci---

.github/workflows/ci.yml

@@ -0,0 +1,59 @@
+name: acdl-ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Compile all Python files
+        run: |
+          python3 -m py_compile \
+            acdl_platform/confidence_signal.py \
+            acdl_platform/outbox_writer.py \
+            adapters/terraform/adapter.py \
+            adapters/terraform/policy/checkov_adapter.py \
+            scripts/push_consumer_image.py
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install test dependencies
+        run: pip install -r requirements-test.txt
+
+      - name: Run pytest
+        run: python3 -m pytest tests/ -v --tb=short
+
+  check-only:
+    name: Platform check-only (offline)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install runtime dependencies
+        run: pip install jsonschema pyyaml boto3
+
+      - name: Run platform check-only
+        run: bash scripts/run_platform.sh --check-only