feat: share credentials with users and roles, inherit data on account deletion (#1342)

* feat: share credentials with users and roles, inherit data on account deletion

Credentials can be shared at "use" or "manage" level. Recipients get
a copy re-encrypted under their own data key (shared_credential_secrets),
kept in step with the owner's row through the same lifecycle hooks as
shared host secrets. One gate, findUsableCredential(), replaces the
private-namespace lookups so a shared credential works wherever a
private one does. Deleting a user now hands their hosts and credentials
to a successor (the deleting admin by default) instead of revoking
everything they shared.

* fix: harden credential ownership transfer

src/ui/locales/en.json

@@ -114,6 +114,32 @@
     "cloneCredentialAction": "Clone credential",
     "clonedCredential": "Cloned {{name}}",
     "clonedCredentialName": "{{name}} (copy)",
+    "shareCredentialAction": "Share credential",
+    "sharedBadge": "shared",
+    "sharedBy": "Shared by {{owner}}",
+    "share": {
+      "title": "Share \"{{name}}\"",
+      "description": "Recipients get their own encrypted copy of the secrets. It is refreshed whenever the credential changes and removed when the share is revoked.",
+      "users": "Users",
+      "roles": "Roles",
+      "searchPlaceholder": "Search...",
+      "permission": "Permission",
+      "levelUse": "Use",
+      "levelManage": "Manage",
+      "levelUseDesc": "Use: attach the credential to hosts and connect. The secret itself stays hidden.",
+      "levelManageDesc": "Manage: also edit the credential and share it with others.",
+      "expires": "Expires",
+      "expiry": {
+        "never": "Never",
+        "oneDay": "1 day",
+        "sevenDays": "7 days",
+        "thirtyDays": "30 days"
+      },
+      "currentAccess": "Shared with",
+      "revoke": "Revoke",
+      "shared": "Credential shared",
+      "shareButton": "Share"
+    },
     "deleteCredentialAction": "Delete credential",
     "editCredentialAction": "Edit credential",
     "failedToCloneCredential": "Failed to clone credential",
@@ -3653,6 +3679,10 @@
     "snippetDeletedSuccess": "Snippet deleted",
     "snippetDeleteFailed": "Failed to delete snippet",
     "noSessionsForUser": "No active sessions",
+    "deleteSuccessorLabel": "Hand over hosts and credentials to",
+    "deleteSuccessorMe": "Me (the deleting admin)",
+    "deleteSuccessorNone": "Nobody — delete them",
+    "deleteSuccessorDesc": "Everything this user shared keeps working under the new owner; choosing nobody removes their hosts, credentials and shares.",
     "deleteUserDangerDesc": "Permanently delete {{username}} and all of their data (hosts, credentials, snippets, history). This cannot be undone.",
     "deleteUserConfirm": "Permanently delete {{username}} and all of their data?",
     "deleteUserAdminBlocked": "Remove admin status before deleting this user.",