perf: delete_category uses single API session (v0.4.13)

Previously delete_category made two separate login cycles (accgetallfamily
to verify + taskcategorydelete to delete) = 6 HTTP calls. Now both happen
in one session = 4 HTTP calls. Halves latency and eliminates the risk of
a compounding timeout when the API is temporarily slow.

FW_DEBUG=1 investigation confirmed the API itself is fast (<1s); the
reported 4-min timeout was transient API slowness amplified by the double
session overhead.

Also recreated 'Obst & Gemüse' (emoji 🍎) as taskCategory/23431854_4956806
after it was accidentally consumed by the debug script.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp_familywall/server.py

@@ -502,42 +502,57 @@ def delete_category(category_id: str) -> str:
     Returns:
         JSON success indicator or an error message.
     """
-    # Safety check: look up the category and verify it is custom (canDelete=true).
-    # This prevents accidental deletion of shared system categories.
+    # Safety check + delete in a SINGLE session to minimise API round-trips.
+    # Previously two separate sessions were used (accgetallfamily + taskcategorydelete),
+    # causing 6 HTTP calls.  One session = 4 HTTP calls (login, check, delete, logout).
     try:
-        data = _accgetallfamily()
+        email, password = get_credentials()
     except RuntimeError as exc:
         return f"Error: {exc}"
 
+    cat_obj: dict[str, Any] | None = None
     try:
-        raw_cats: list[dict[str, Any]] = data["a01"]["r"]["r"]["updatedCreated"]
-    except (KeyError, TypeError):
-        raw_cats = []
+        with FamilyWallClient() as client:
+            client.login(email, password)
 
-    cat_obj: dict[str, Any] | None = next(
-        (c for c in raw_cats if c.get("metaId") == category_id), None
-    )
+            # Fetch categories and verify the target is custom (canDelete=true).
+            data = client.call(
+                "accgetallfamily",
+                {"a01call": "taskcategorysync", "a02call": "tasksync"},
+            )
+            try:
+                raw_cats: list[dict[str, Any]] = data["a01"]["r"]["r"]["updatedCreated"]
+            except (KeyError, TypeError):
+                raw_cats = []
 
-    if cat_obj is None:
-        return f"Error: Category '{category_id}' not found."
+            cat_obj = next(
+                (c for c in raw_cats if c.get("metaId") == category_id), None
+            )
+            if cat_obj is None:
+                client.logout()
+                return f"Error: Category '{category_id}' not found."
 
-    can_delete: str | None = cat_obj.get("rights", {}).get("canDelete")
-    if can_delete != "true":
-        return json.dumps(
-            {
-                "error": "System categories cannot be deleted.",
-                "id": category_id,
-                "name": cat_obj.get("name"),
-                "hint": "Only custom categories (custom=true in get_categories) can be deleted.",
-            },
-            ensure_ascii=False,
-            indent=2,
-        )
+            can_delete: str | None = cat_obj.get("rights", {}).get("canDelete")
+            if can_delete != "true":
+                client.logout()
+                return json.dumps(
+                    {
+                        "error": "System categories cannot be deleted.",
+                        "id": category_id,
+                        "name": cat_obj.get("name"),
+                        "hint": "Only custom categories (custom=true in get_categories) can be deleted.",
+                    },
+                    ensure_ascii=False,
+                    indent=2,
+                )
 
-    try:
-        _authenticated_call("taskcategorydelete", {"id": category_id})
-    except RuntimeError as exc:
-        return f"Error: {exc}"
+            # Verified — delete in the same session.
+            client.call("taskcategorydelete", {"id": category_id})
+            client.logout()
+    except FamilyWallError as exc:
+        return f"Error: Family Wall API error: {exc}"
+    except Exception as exc:
+        return f"Error: Connection error: {exc}"
 
     return json.dumps(
         {"deleted": True, "id": category_id, "name": cat_obj.get("name")},