chore: simayi-approved changes - lint fixes, toolchain improvements, healthz

All changes reviewed and APPROVED in PR #12 (Review ID: 40):
- toolchain_routes: webhook repo/org format compat, content dedup (sha256), closed issue filter
- dispatcher: inform mail crash 误标 done 修复
- ticker: cleanup and improvements
- healthz endpoint
- conftest: integration/e2e deselect markers
- docs: design docs, test-guide updates
- various lint/whitespace fixes across 30 files

tests/conftest.py

@@ -55,6 +55,21 @@ def client_with_isolation(isolated_data_root):
 
 # ── E2E gate ──
 
+def pytest_collection_modifyitems(config, items):
+    if not os.environ.get("RUN_INTEGRATION"):
+        skip_reason = "needs RUN_INTEGRATION=1"
+        remaining = []
+        deselected = []
+        for item in items:
+            if "integration" in item.keywords or "e2e" in item.keywords:
+                deselected.append(item)
+            else:
+                remaining.append(item)
+        if deselected:
+            config.hook.pytest_deselected(items=deselected)
+            items[:] = remaining
+
+
 skip_no_integration = pytest.mark.skipif(
     not os.environ.get("RUN_INTEGRATION"),
     reason="Set RUN_INTEGRATION=1 to run E2E tests against real daemon",