feat(hooks): data-hp="mode-tab" + data-mode на вкладках режимов редакторов (#629)

Единственная дыра контракта #489 для тестового фасада харнесса: у вкладок
plan/devices/decor был только data-editor-navigation, которого нет в JSON-
контракте. Хук описан в docs/data-hp-contract.json (audience test, since
1.78.0-beta.2) и STYLING-HOOKS §7.4; присутствует только вместе с самими
вкладками (право на редактирование). Стилями не выбирается, пикселей не
меняет. Бандл пересобран.

Issue: #629
User-Visible: no

docs/STYLING-HOOKS.md

@@ -405,6 +405,11 @@ use `[data-hp="tool"][data-tool="…"]`; the complete `data-tool` vocabulary is
 in the JSON inventory. The toolbar X and the X on the active mode tab use
 `[data-hp="editor-close"]` while retaining `data-editor-navigation="view"`.
 
+The three editor mode tabs are `[data-hp="mode-tab"][data-mode="plan|devices|decor"]`
+(#629) and keep `data-editor-navigation`. Like the tabs themselves, the hook is
+present only for a user allowed to edit. Nothing in the card's styles selects
+it; its audience is `test`.
+
 The one visible secondary/context surface uses `[data-hp="tray"]`. Its
 `data-kind` is the stable launcher id when a grouped launcher owns it and the
 broad secondary kind otherwise. A closed placeholder does not carry the hook.

docs/data-hp-contract.json

@@ -69,6 +69,12 @@
       "since": "1.73.0-beta.7",
       "audience": ["test"]
     },
+    "mode-tab": {
+      "elements": ["button"],
+      "since": "1.78.0-beta.2",
+      "audience": ["test"],
+      "attributes": { "data-mode": ["plan", "devices", "decor"] }
+    },
     "opening": {
       "elements": ["g"],
       "since": "1.59.0-beta.3",