feat(sprint-5): Phase 6 — Staff management UI (list, invite, permissions, revoke)

- /settings/staff: staff account table with role badges + permission chips
- Invite sheet: email + role template + 8 granular permission checkboxes
- Edit permissions dialog with optimistic update
- Revoke access with AlertDialog confirmation
- React Query hooks wired (useStaffListQuery, mutations)
- Full i18n (de/en), mock fallback, loading skeletons
- Sidebar nav updated: Personal → /settings/staff with UserCog icon
- Added @radix-ui/react-checkbox + Checkbox UI component

cannamanage-frontend/messages/en.json

@@ -293,6 +293,45 @@
     "footerText": "Cannabis cultivation club — Secure member management",
     "adminLogin": "Go to Admin Login"
   },
+  "staff": {
+    "title": "Staff",
+    "invite": "Invite New Member",
+    "name": "Name",
+    "email": "Email",
+    "role": "Role",
+    "permissions": "Permissions",
+    "status": "Status",
+    "actions": "Actions",
+    "active": "Active",
+    "revoked": "Revoked",
+    "invited": "Invited",
+    "editPermissions": "Edit Permissions",
+    "revokeAccess": "Revoke Access",
+    "revokeConfirm": "Really revoke access for {name}? The staff member will no longer be able to sign in.",
+    "revokeSuccess": "Access revoked.",
+    "inviteTitle": "Invite Staff Member",
+    "inviteDesc": "Invite a new team member via email and assign permissions.",
+    "inviteEmail": "Email address",
+    "inviteRole": "Role template",
+    "roleAusgabe": "Distribution",
+    "roleLager": "Stock",
+    "roleVorstand": "Board",
+    "roleCustom": "Custom",
+    "inviteSend": "Send Invitation",
+    "inviteSuccess": "Invitation sent to {email}.",
+    "permRecordDistribution": "Record Distribution",
+    "permViewMemberList": "View Member List",
+    "permViewMemberQuota": "View Quota",
+    "permAddMember": "Add Members",
+    "permViewStock": "View Stock",
+    "permRecordStockIn": "Record Stock In",
+    "permViewComplianceReport": "View Reports",
+    "permManageGrowCalendar": "Manage Grow Calendar",
+    "savePermissions": "Save",
+    "permissionsSaved": "Permissions updated.",
+    "cancel": "Cancel",
+    "noStaff": "No staff members yet."
+  },
   "api": {
     "loading": "Loading...",
     "error": "Failed to load data.",