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---

tests/conftest.py

@@ -0,0 +1,34 @@
+import json
+import os
+import sys
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(ROOT))
+
+
+@pytest.fixture
+def repo_root():
+    return str(ROOT)
+
+
+@pytest.fixture
+def spike_ir():
+    return json.load(open(ROOT / "modules-ir/l1/l1-s3/spike_instance.json"))
+
+
+@pytest.fixture
+def ir_schema():
+    return json.load(open(ROOT / "schemas/ir.schema.json"))
+
+
+@pytest.fixture
+def registry():
+    return json.load(open(ROOT / "modules-ir/registry.json"))
+
+
+@pytest.fixture
+def policy_check_result_schema():
+    return json.load(open(ROOT / "schemas/policy_check_result.schema.json"))