test(observability): validate sidebar route coverage

docs/guides/observability_ui_governance.md

@@ -67,6 +67,7 @@ Guard 會檢查：
 - 側欄是否維持暖深咖啡背景與第二/三層足夠對比。
 - Topbar 是否仍載入觀測台 CSS 與健康 indicator。
 - 10 個觀測頁的 `active_page`、側欄 URL、側欄 label、`momo-observability-mode` 掛載清單是否一一對齊。
+- 10 個側欄 URL 是否都在 `routes/admin_observability_routes.py` 有對應 Flask route。
 
 ### 2. Production 10 頁 HTTP 巡檢
 

scripts/check_observability_ui.py

@@ -246,6 +246,15 @@ def scan_nav_contract() -> list[str]:
         if active_page not in base_text:
             findings.append(f"{BASE_PATH}: momo-observability-mode list missing `{active_page}`")
 
+        route_suffix = url.replace("/observability", "", 1) or "/"
+        route_pattern = re.compile(
+            r"@admin_observability_bp\.route\(\s*['\"]"
+            + re.escape(route_suffix)
+            + r"['\"]"
+        )
+        if route_text and not route_pattern.search(route_text):
+            findings.append(f"{ROUTE_PATH}: missing route `{route_suffix}` for `{label}`")
+
     sidebar_observability_links = set(re.findall(r'href="(/observability/[^"]+)"', shell_text))
     expected_links = {url for _, _, url, _ in OBSERVABILITY_NAV_ITEMS}
     extra_links = sorted(sidebar_observability_links - expected_links)