Gate project override settings to owners and admins

Why: S9 acceptance finding 3 — the project settings modal exposed the
host override settings (including the model/key group, masked) to plain
project members; the duties data plane was already permission-enforced,
but the host settings surface had no gate.

Evidence: vitest 34 files / 293 tests pass with the change; tsc reports
no errors in the modified file. Ruling per the acceptance plan P1-B:
the modal entry stays (granted duty managers need the RDM tabs), while
the host override settings group renders only for the project owner or
a system admin; RDM tabs keep their own fail-closed gating.

Impact: ProjectSettingsModal project tab renders an explanatory empty
state for non-privileged viewers; members/duties/matrix tabs unchanged.
Refs: S9 acceptance report P1-B

src/components/ProjectSettingsModal.tsx

@@ -19,6 +19,11 @@ export function ProjectSettingsModal() {
   const rdmDocReviewAvailable = useStore(s => s.rdmDocReviewAvailable)
   const rdmPermMatrixAvailable = useStore(s => s.rdmPermMatrixAvailable)
   const owner = useStore(s => s.me?.owner)
+  const isAdmin = useStore(s => s.me?.isAdmin ?? false)
+  // P1-B 裁定：宿主覆盖设置（含模型与密钥）仅项目负责人/系统管理员可查看与修改；
+  // RDM 页签（成员/文档职责/项目权限）不在此列——数据面由 RDM 权限自行收敛，
+  // 授权的职责管理者仍可进入。
+  const projectPrivileged = !!project && (project.owner === owner || isAdmin)
   const [tab, setTab] = useState('project')
   const [schema, setSchema] = useState<SettingDesc[]>([])
   const [draft, setDraft] = useState<Record<string, any>>({})
@@ -85,6 +90,8 @@ export function ProjectSettingsModal() {
         </>}
         {tab !== 'members' && tab !== 'duties' && tab !== 'matrix' && !loaded ? (
           <EmptyState icon="settings">{error || '加载中…'}</EmptyState>
+        ) : tab !== 'members' && tab !== 'duties' && tab !== 'matrix' && !projectPrivileged ? (
+          <EmptyState icon="settings">项目覆盖设置（含模型与密钥）仅项目负责人或系统管理员可查看与修改。</EmptyState>
         ) : tab !== 'members' && tab !== 'duties' && tab !== 'matrix' ? (
           <>
             <div className="empty-note" style={{ marginBottom: 10 }}>