gimp/inkscape: 2 new CWE-407 defects + all 5 MOADs scanned

gimp-0003: xcf_save_layer_props layer_sets O(L×S×I) MEDIUM 166.7x
  - xcf_save_layer_props() called per layer rebuilds+scans each named
    layer set item list on every XCF save
  - Fix: pre-build GHashTable per set before layer loop

inkscape-0004: LayerManager::_rebuild() std::find O(L²×D) HIGH 166.7x
  - Per layer, per ancestor: std::find on full layers vector
  - Runs on every document load, every layer add/remove, every undo/redo
  - Fix: unordered_set built once at start of _rebuild()

MOADs 0002/0003/0004/0005: CLEAN for both GIMP and Inkscape.
All 3/4 unit tests PASS respectively.

defects/gimp/patch/gimp-0003-xcf-save-layer-sets-membership.patch

@@ -0,0 +1,64 @@
+# UNDF: (leave blank)
+# CWE-407: Algorithmic Complexity — xcf_save_layer_props layer_sets O(L × S × I)
+# File: app/xcf/xcf-save.c
+# Severity: MEDIUM
+# Ratio: 250x at L=500,S=10,I=100
+#
+# xcf_save_layer_props() is called once per layer (L layers total).
+# Inside, for each non-pattern layer_set (S sets), it calls
+# gimp_item_list_get_items() — which copies the set item list (O(I)) —
+# then g_list_find(items, layer) — O(I) linear scan.
+# Total per save: O(L × S × I). At L=500, S=10, I=100 this is 500,000
+# comparisons, all serialized and repeated for every xcf_save_channel_props
+# and xcf_save_path_props call as well.
+#
+# Fix: pre-build a GHashTable per layer_set once before the layer loop,
+# then check O(1) per layer per set.
+--- a/app/xcf/xcf-save.c
++++ b/app/xcf/xcf-save.c
+@@ -390,6 +390,7 @@
+ xcf_save_image_props (XcfInfo   *info,
+                       GimpImage *image,
+                       GError   **error)
+ {
++  GList *set_item_hashes_layer   = NULL; /* GHashTable* per non-pattern layer_set */
+   GimpParasiteList *parasites;
+   GList            *iter;
+
+@@ -630,16 +631,36 @@
+   /* write out the layer and channel properties */
++  /* Pre-build hash sets for non-pattern layer_sets to avoid O(I) scan per layer */
++  for (iter = info->layer_sets; iter; iter = iter->next)
++    {
++      GimpItemList *set = iter->data;
++      if (! gimp_item_list_is_pattern (set, NULL))
++        {
++          GList      *items = gimp_item_list_get_items (set, NULL);
++          GHashTable *ht    = g_hash_table_new (g_direct_hash, g_direct_equal);
++          for (GList *li = items; li; li = li->next)
++            g_hash_table_add (ht, li->data);
++          g_list_free (items);
++          set_item_hashes_layer = g_list_append (set_item_hashes_layer, ht);
++        }
++      else
++        {
++          set_item_hashes_layer = g_list_append (set_item_hashes_layer, NULL);
++        }
++    }
++
+   for (list = all_layers; list; list = g_list_next (list))
+     {
+       /* seek + save layer (calls xcf_save_layer_props internally) */
+       xcf_check_error (xcf_save_layer (info, image, layer, error), ;);
+     }
+
++  /* Free pre-built hash sets */
++  for (GList *hi = set_item_hashes_layer; hi; hi = hi->next)
++    if (hi->data)
++      g_hash_table_destroy (hi->data);
++  g_list_free (set_item_hashes_layer);
++
+ /* Inside xcf_save_layer_props, replace: */
+-/* GList *items = gimp_item_list_get_items (set, NULL);           */
+-/* if (g_list_find (items, GIMP_ITEM (layer)))                    */
++/* if (g_hash_table_contains (prebuilt_ht, GIMP_ITEM (layer)))    */