032: fix 2 critical QA issues — missing endregion + Tombstone dead helpers

C1: _llm_call.py — added missing #endregion _split_and_retry (violated INV_3)
C2: dashboards/_helpers.py — sync _find_dashboard_id_by_slug and
    _resolve_dashboard_id_from_ref typed Tombstone per INV_6 (dead code,
    callers use _async versions from git/_helpers.py)

backend/src/api/routes/dashboards/_helpers.py

@@ -12,51 +12,39 @@ from src.core.async_superset_client import AsyncSupersetClient
 from src.core.superset_client import SupersetClient
 
 
-# #region _find_dashboard_id_by_slug [C:2] [TYPE Function]
-# @BRIEF Resolve dashboard numeric ID by slug using Superset list endpoint.
-# @PRE  `dashboard_slug` is non-empty.
-# @POST  Returns dashboard ID when found, otherwise None.
+# #region _find_dashboard_id_by_slug [C:2] [TYPE Tombstone]
+# @DEPRECATED 2026-06-04 — replaced by _find_dashboard_id_by_slug_async
+# @REPLACED_BY -> [_find_dashboard_id_by_slug_async]
+# @BRIEF Resolve dashboard numeric ID by slug — sync version, dead code.
+# Body removed: SupersetClient methods are now async; this function
+# would raise AttributeError at runtime.
 def _find_dashboard_id_by_slug(
     client: SupersetClient,
     dashboard_slug: str,
 ) -> int | None:
-    """@DEPRECATED — dead code, use _find_dashboard_id_by_slug_async."""
-    # This function is no longer called (only _async version is used).
-    # It remains as a reference but will raise AttributeError at runtime
-    # because SupersetClient methods are now async.
-    query_variants = [
-        {
-            "filters": [{"col": "slug", "opr": "eq", "value": dashboard_slug}],
-            "page": 0,
-            "page_size": 1,
-        },
-        {
-            "filters": [{"col": "slug", "op": "eq", "value": dashboard_slug}],
-            "page": 0,
-            "page_size": 1,
-        },
-    ]
-
-    for query in query_variants:
-        try:
-            _count, dashboards = client.get_dashboards_page(query=query)
-            if dashboards:
-                resolved_id = dashboards[0].get("id")
-                if resolved_id is not None:
-                    return int(resolved_id)
-        except Exception:
-            continue
-
-    return None
+    raise RuntimeError(
+        "_find_dashboard_id_by_slug is deprecated. "
+        "Use _find_dashboard_id_by_slug_async() instead."
+    )
 
 
 # #endregion _find_dashboard_id_by_slug
 
 
-# #region _resolve_dashboard_id_from_ref [C:2] [TYPE Function]
-# @BRIEF Resolve dashboard ID from slug-first reference with numeric fallback.
-# @PRE  `dashboard_ref` is provided in route path.
-# @POST  Returns a valid dashboard ID or raises HTTPException(404).
+# #region _resolve_dashboard_id_from_ref [C:2] [TYPE Tombstone]
+# @DEPRECATED 2026-06-04 — replaced by _resolve_dashboard_id_from_ref_async
+# @REPLACED_BY -> [_resolve_dashboard_id_from_ref_async]
+# @BRIEF Resolve dashboard ID from slug-first reference — sync version, dead code.
+# Body removed: SupersetClient methods are now async; this function
+# would raise AttributeError at runtime.
+def _resolve_dashboard_id_from_ref(
+    client: SupersetClient,
+    dashboard_ref: str,
+) -> int:
+    raise RuntimeError(
+        "_resolve_dashboard_id_from_ref is deprecated. "
+        "Use _resolve_dashboard_id_from_ref_async() instead."
+    )
 def _resolve_dashboard_id_from_ref(
     dashboard_ref: str,
     client: SupersetClient,

backend/src/plugins/translate/_llm_call.py

@@ -278,6 +278,8 @@ class LLMTranslationService:
                 "skipped": left["skipped"] + right["skipped"],
                 "retries": retries + left.get("retries", 0) + right.get("retries", 0)}
 
+    # #endregion _split_and_retry
+
     # #region _try_recover_partial [C:3] [TYPE Function] [SEMANTICS translate, llm, recovery]
     # @BRIEF Try to recover translated rows from a truncated LLM response.
     #        Saves recovered rows as SUCCESS records. Returns set of recovered row_index values.