feat: folder shares apply to hosts added later (#1343)

* feat: folder shares apply to hosts added later

Sharing a folder only fanned grants out to the hosts in it at the time.
The share is now also kept as a standing rule on the folder, and a host
created in or moved into it (or a subfolder) inherits the same access
and secret snapshots. Rules follow folder renames and can be stopped
from the share dialog.

* fix: stabilize folder access migrations

src/ui/locales/en.json

@@ -1611,6 +1611,9 @@
       "shareWithCount": "Share ({{count}})",
       "currentAccess": "Current access",
       "noAccessEntries": "This host has not been shared yet",
+      "folderRulesTitle": "Applies to hosts added later",
+      "folderRulesHint": "These shares stay on the folder: a host created in or moved into it (or a subfolder) gets the same access automatically. Removing a rule only stops future inheritance.",
+      "folderRuleRemove": "Stop inheriting",
       "folderShareSummary": "Shared {{shared}} of {{total}} host(s) in this folder",
       "grantedBy": "Granted by",
       "expires": "Expires",