test: фаза 4 — тесты extractors, ecosystem, i18n, metrics

- test_nexus.py: extract_pypi/go/npm, dispatch, edge cases (16 тестов)
- test_i18n.py: RU/EN переводы, fallback, форматирование, web UI (10 тестов)
- test_metrics.py: Prometheus endpoint (4 теста)
- test_webhooks.py: _detect_ecosystem (6 тестов), Go/npm webhook fixtures
- conftest.py: sample_nexus_go/npm_webhook fixtures
- Всего: 85 тестов (было 50)

tests/conftest.py

@@ -209,3 +209,39 @@ def guarddog_normalized_clean():
         "findings": [],
         "errors": [],
     }
+
+
+@pytest.fixture
+def sample_nexus_go_webhook():
+    return {
+        "timestamp": "2026-05-10T12:00:00.000+00:00",
+        "nodeId": "test-node",
+        "initiator": "admin",
+        "action": "UPDATED",
+        "repositoryName": "go-proxy",
+        "asset": {
+            "id": "go123",
+            "assetId": "Z28xMjM=",
+            "format": "go",
+            "name": "/packages/github.com/gorilla/mux/@v/v1.8.0.zip",
+            "downloadUrl": "http://nexus:8081/repository/go-proxy/github.com/gorilla/mux/@v/v1.8.0.zip",
+        },
+    }
+
+
+@pytest.fixture
+def sample_nexus_npm_webhook():
+    return {
+        "timestamp": "2026-05-10T12:00:00.000+00:00",
+        "nodeId": "test-node",
+        "initiator": "admin",
+        "action": "UPDATED",
+        "repositoryName": "npm-proxy",
+        "asset": {
+            "id": "npm123",
+            "assetId": "bnBtMTIz",
+            "format": "npm",
+            "name": "/packages/lodash/-/lodash-4.17.21.tgz",
+            "downloadUrl": "http://nexus:8081/repository/npm-proxy/lodash/-/lodash-4.17.21.tgz",
+        },
+    }